diff --git a/Libraries/Renderer/REVISION b/Libraries/Renderer/REVISION
index 8674d35ac6df0e..87635b7092acec 100644
--- a/Libraries/Renderer/REVISION
+++ b/Libraries/Renderer/REVISION
@@ -1 +1 @@
-c1220ebdde506de91c8b9693b5cb67ac710c8c89
\ No newline at end of file
+a049aa015563c2e50f44214c28d186c0bae09ba6
\ No newline at end of file
diff --git a/Libraries/Renderer/implementations/ReactFabric-dev.fb.js b/Libraries/Renderer/implementations/ReactFabric-dev.fb.js
index 3c37320dbd2ef3..03179428b6d2b9 100644
--- a/Libraries/Renderer/implementations/ReactFabric-dev.fb.js
+++ b/Libraries/Renderer/implementations/ReactFabric-dev.fb.js
@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<c63c5718d1b40bee38ff92020247d874>>
+ * @generated SignedSource<<4b47cfe3313108f4cdeb2cfc4dfea2e5>>
  */
 
 'use strict';
@@ -156,7 +156,7 @@ var invokeGuardedCallbackImpl = invokeGuardedCallbackProd;
       // when we call document.createEvent(). However this can cause confusing
       // errors: https://github.com/facebook/create-react-app/issues/3482
       // So we preemptively throw with a better message instead.
-      if (typeof document === "undefined") {
+      if (typeof document === "undefined" || document === null) {
         throw new Error(
           "The `document` global was defined when React was initialized, but is not " +
             "defined anymore. This can happen in a test environment if a component " +
@@ -2868,6 +2868,7 @@ var enableProfilerCommitHooks = true;
 var enableLazyElements = false;
 var warnAboutStringRefs = false;
 var warnOnSubscriptionInsideStartTransition = false;
+var enableSuspenseAvoidThisFallback = false;
 var enableNewReconciler = false;
 var enableLazyContextPropagation = false;
 
@@ -6008,7 +6009,7 @@ function flushSyncCallbacks() {
   return null;
 }
 
-var ReactVersion = "18.0.0-c1220ebdd-20211123";
+var ReactVersion = "18.0.0-rc.0-a049aa015-20211213";
 
 var SCHEDULING_PROFILER_VERSION = 1;
 
@@ -10448,16 +10449,9 @@ function shouldCaptureSuspense(workInProgress, hasInvisibleParent) {
 
   var props = workInProgress.memoizedProps; // Regular boundaries always capture.
 
-  if (props.unstable_avoidThisFallback !== true) {
+  {
     return true;
   } // If it's a boundary we should avoid, then we prefer to bubble up to the
-  // parent boundary if it is currently invisible.
-
-  if (hasInvisibleParent) {
-    return false;
-  } // If the parent is not able to handle it, we must handle it.
-
-  return true;
 }
 function findFirstSuspended(row) {
   var node = row;
@@ -12206,12 +12200,19 @@ function getIsUpdatingOpaqueValueInRenderPhaseInDEV() {
 
 function mountId() {
   var hook = mountWorkInProgressHook();
+  var root = getWorkInProgressRoot(); // TODO: In Fizz, id generation is specific to each server config. Maybe we
+  // should do this in Fiber, too? Deferring this decision for now because
+  // there's no other place to store the prefix except for an internal field on
+  // the public createRoot object, which the fiber tree does not currently have
+  // a reference to.
+
+  var identifierPrefix = root.identifierPrefix;
   var id;
 
   {
     // Use a lowercase r prefix for client-generated ids.
     var globalClientId = globalClientIdCounter++;
-    id = "r:" + globalClientId.toString(32);
+    id = identifierPrefix + "r:" + globalClientId.toString(32);
   }
 
   hook.memoizedState = id;
@@ -13742,16 +13743,9 @@ function resetSuspendedComponent(sourceFiber, rootRenderLanes) {
 
 function getNearestSuspenseBoundaryToCapture(returnFiber) {
   var node = returnFiber;
-  var hasInvisibleParentBoundary = hasSuspenseContext(
-    suspenseStackCursor.current,
-    InvisibleParentSuspenseContext
-  );
 
   do {
-    if (
-      node.tag === SuspenseComponent &&
-      shouldCaptureSuspense(node, hasInvisibleParentBoundary)
-    ) {
+    if (node.tag === SuspenseComponent && shouldCaptureSuspense(node)) {
       return node;
     } // This boundary already captured during this render. Continue to the next
     // boundary.
@@ -14743,7 +14737,8 @@ function completeWork(current, workInProgress, renderLanes) {
           // should be able to immediately restart from within throwException.
           var hasInvisibleChildContext =
             current === null &&
-            workInProgress.memoizedProps.unstable_avoidThisFallback !== true;
+            (workInProgress.memoizedProps.unstable_avoidThisFallback !== true ||
+              !enableSuspenseAvoidThisFallback);
 
           if (
             hasInvisibleChildContext ||
@@ -16566,7 +16561,7 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
       // Mark this subtree context as having at least one invisible parent that could
       // handle the fallback state.
       // Avoided boundaries are not considered since they cannot handle preferred fallback states.
-      if (nextProps.unstable_avoidThisFallback !== true) {
+      {
         suspenseContext = addSubtreeSuspenseContext(
           suspenseContext,
           InvisibleParentSuspenseContext
@@ -23531,7 +23526,7 @@ function assignFiberPropertiesInDEV(target, source) {
   return target;
 }
 
-function FiberRootNode(containerInfo, tag, hydrate) {
+function FiberRootNode(containerInfo, tag, hydrate, identifierPrefix) {
   this.tag = tag;
   this.containerInfo = containerInfo;
   this.pendingChildren = null;
@@ -23554,6 +23549,7 @@ function FiberRootNode(containerInfo, tag, hydrate) {
   this.finishedLanes = NoLanes;
   this.entangledLanes = NoLanes;
   this.entanglements = createLaneMap(NoLanes);
+  this.identifierPrefix = identifierPrefix;
 
   {
     this.effectDuration = 0;
@@ -23588,9 +23584,10 @@ function createFiberRoot(
   hydrate,
   hydrationCallbacks,
   isStrictMode,
-  concurrentUpdatesByDefaultOverride
+  concurrentUpdatesByDefaultOverride,
+  identifierPrefix
 ) {
-  var root = new FiberRootNode(containerInfo, tag, hydrate);
+  var root = new FiberRootNode(containerInfo, tag, hydrate, identifierPrefix);
   // stateNode is any.
 
   var uninitializedFiber = createHostRootFiber(
@@ -23737,7 +23734,8 @@ function createContainer(
   hydrate,
   hydrationCallbacks,
   isStrictMode,
-  concurrentUpdatesByDefaultOverride
+  concurrentUpdatesByDefaultOverride,
+  identifierPrefix
 ) {
   return createFiberRoot(
     containerInfo,
@@ -23745,7 +23743,8 @@ function createContainer(
     hydrate,
     hydrationCallbacks,
     isStrictMode,
-    concurrentUpdatesByDefaultOverride
+    concurrentUpdatesByDefaultOverride,
+    identifierPrefix
   );
 }
 function updateContainer(element, container, parentComponent, callback) {
@@ -24539,7 +24538,8 @@ function render(element, containerTag, callback, concurrentRoot) {
       false,
       null,
       false,
-      null
+      null,
+      ""
     );
     roots.set(containerTag, root);
   }
@@ -24603,6 +24603,6 @@ if (
 ) {
   __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop(new Error());
 }
-
+        
   })();
 }
diff --git a/Libraries/Renderer/implementations/ReactFabric-prod.fb.js b/Libraries/Renderer/implementations/ReactFabric-prod.fb.js
index 8a9e075a5089e4..9bf33ee0ddecf1 100644
--- a/Libraries/Renderer/implementations/ReactFabric-prod.fb.js
+++ b/Libraries/Renderer/implementations/ReactFabric-prod.fb.js
@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<d2675ef49da99531a7fa8940f853bd5f>>
+ * @generated SignedSource<<91162956144e0110fdc5f76b4de6f80e>>
  */
 
 "use strict";
@@ -4076,9 +4076,11 @@ var ContextOnlyDispatcher = {
     },
     useSyncExternalStore: mountSyncExternalStore,
     useId: function() {
-      var hook = mountWorkInProgressHook();
-      var id = "r:" + (globalClientIdCounter++).toString(32);
-      return (hook.memoizedState = id);
+      var hook = mountWorkInProgressHook(),
+        identifierPrefix = workInProgressRoot.identifierPrefix,
+        globalClientId = globalClientIdCounter++;
+      identifierPrefix = identifierPrefix + "r:" + globalClientId.toString(32);
+      return (hook.memoizedState = identifierPrefix);
     },
     unstable_isNewReconciler: !1
   },
@@ -4620,11 +4622,7 @@ function completeWork(current, workInProgress, renderLanes) {
         !renderLanes &&
         ((workInProgress.child.flags |= 8192), 0 !== (workInProgress.mode & 1))
       )
-        if (
-          (null === current &&
-            !0 !== workInProgress.memoizedProps.unstable_avoidThisFallback) ||
-          0 !== (suspenseStackCursor.current & 1)
-        )
+        if (null === current || 0 !== (suspenseStackCursor.current & 1))
           0 === workInProgressRootExitStatus &&
             (workInProgressRootExitStatus = 3);
         else {
@@ -5321,11 +5319,9 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
       null !== current && null === current.memoizedState
         ? !1
         : 0 !== (suspenseContext & 2));
-  JSCompiler_temp
-    ? ((showFallback = !0), (workInProgress.flags &= -129))
-    : (null !== current && null === current.memoizedState) ||
-      !0 === nextProps.unstable_avoidThisFallback ||
-      (suspenseContext |= 1);
+  if (JSCompiler_temp) (showFallback = !0), (workInProgress.flags &= -129);
+  else if (null === current || null !== current.memoizedState)
+    suspenseContext |= 1;
   push(suspenseStackCursor, suspenseContext & 1);
   if (null === current) {
     current = nextProps.children;
@@ -6782,8 +6778,6 @@ function handleError(root$jscomp$0, thrownValue) {
           }
           b: {
             sourceFiber$jscomp$0 = returnFiber;
-            var hasInvisibleParentBoundary =
-              0 !== (suspenseStackCursor.current & 1);
             do {
               var JSCompiler_temp;
               if ((JSCompiler_temp = 13 === sourceFiber$jscomp$0.tag)) {
@@ -6793,12 +6787,6 @@ function handleError(root$jscomp$0, thrownValue) {
                     ? null !== nextState.dehydrated
                       ? !0
                       : !1
-                    : !0 !==
-                      sourceFiber$jscomp$0.memoizedProps
-                        .unstable_avoidThisFallback
-                    ? !0
-                    : hasInvisibleParentBoundary
-                    ? !1
                     : !0;
               }
               if (JSCompiler_temp) {
@@ -7957,7 +7945,7 @@ function createFiberFromPortal(portal, mode, lanes) {
   };
   return mode;
 }
-function FiberRootNode(containerInfo, tag, hydrate) {
+function FiberRootNode(containerInfo, tag, hydrate, identifierPrefix) {
   this.tag = tag;
   this.containerInfo = containerInfo;
   this.finishedWork = this.pingCache = this.current = this.pendingChildren = null;
@@ -7970,6 +7958,7 @@ function FiberRootNode(containerInfo, tag, hydrate) {
   this.expirationTimes = createLaneMap(-1);
   this.entangledLanes = this.finishedLanes = this.mutableReadLanes = this.expiredLanes = this.pingedLanes = this.suspendedLanes = this.pendingLanes = 0;
   this.entanglements = createLaneMap(0);
+  this.identifierPrefix = identifierPrefix;
 }
 function createPortal(children, containerInfo, implementation) {
   var key =
@@ -8176,7 +8165,7 @@ var roots = new Map(),
   devToolsConfig$jscomp$inline_925 = {
     findFiberByHostInstance: getInstanceFromInstance,
     bundleType: 0,
-    version: "18.0.0-c1220ebdd-20211123",
+    version: "18.0.0-rc.0-a049aa015-20211213",
     rendererPackageName: "react-native-renderer",
     rendererConfig: {
       getInspectorDataForViewTag: function() {
@@ -8191,7 +8180,7 @@ var roots = new Map(),
       }.bind(null, findNodeHandle)
     }
   };
-var internals$jscomp$inline_1179 = {
+var internals$jscomp$inline_1178 = {
   bundleType: devToolsConfig$jscomp$inline_925.bundleType,
   version: devToolsConfig$jscomp$inline_925.version,
   rendererPackageName: devToolsConfig$jscomp$inline_925.rendererPackageName,
@@ -8218,19 +8207,19 @@ var internals$jscomp$inline_1179 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.0.0-c1220ebdd-20211123"
+  reconcilerVersion: "18.0.0-rc.0-a049aa015-20211213"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
-  var hook$jscomp$inline_1180 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
+  var hook$jscomp$inline_1179 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
   if (
-    !hook$jscomp$inline_1180.isDisabled &&
-    hook$jscomp$inline_1180.supportsFiber
+    !hook$jscomp$inline_1179.isDisabled &&
+    hook$jscomp$inline_1179.supportsFiber
   )
     try {
-      (rendererID = hook$jscomp$inline_1180.inject(
-        internals$jscomp$inline_1179
+      (rendererID = hook$jscomp$inline_1179.inject(
+        internals$jscomp$inline_1178
       )),
-        (injectedHook = hook$jscomp$inline_1180);
+        (injectedHook = hook$jscomp$inline_1179);
     } catch (err) {}
 }
 exports.createPortal = function(children, containerTag) {
@@ -8270,7 +8259,7 @@ exports.render = function(element, containerTag, callback, concurrentRoot) {
   var root = roots.get(containerTag);
   root ||
     ((root = concurrentRoot ? 1 : 0),
-    (concurrentRoot = new FiberRootNode(containerTag, root, !1)),
+    (concurrentRoot = new FiberRootNode(containerTag, root, !1, "")),
     (root = createFiber(3, null, null, 1 === root ? 1 : 0)),
     (concurrentRoot.current = root),
     (root.stateNode = concurrentRoot),
diff --git a/Libraries/Renderer/implementations/ReactFabric-profiling.fb.js b/Libraries/Renderer/implementations/ReactFabric-profiling.fb.js
index 0c2802b874b4c8..5fdf10907353ed 100644
--- a/Libraries/Renderer/implementations/ReactFabric-profiling.fb.js
+++ b/Libraries/Renderer/implementations/ReactFabric-profiling.fb.js
@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<d9e820a361c20b62bc9a8c1f8ab34868>>
+ * @generated SignedSource<<7638d79ef666eac85302b8ce3706cab0>>
  */
 
 
@@ -4263,9 +4263,11 @@ var ContextOnlyDispatcher = {
     },
     useSyncExternalStore: mountSyncExternalStore,
     useId: function() {
-      var hook = mountWorkInProgressHook();
-      var id = "r:" + (globalClientIdCounter++).toString(32);
-      return (hook.memoizedState = id);
+      var hook = mountWorkInProgressHook(),
+        identifierPrefix = workInProgressRoot.identifierPrefix,
+        globalClientId = globalClientIdCounter++;
+      identifierPrefix = identifierPrefix + "r:" + globalClientId.toString(32);
+      return (hook.memoizedState = identifierPrefix);
     },
     unstable_isNewReconciler: !1
   },
@@ -4907,11 +4909,7 @@ function completeWork(current, workInProgress, renderLanes) {
         !renderLanes &&
         ((workInProgress.child.flags |= 8192), 0 !== (workInProgress.mode & 1))
       )
-        if (
-          (null === current &&
-            !0 !== workInProgress.memoizedProps.unstable_avoidThisFallback) ||
-          0 !== (suspenseStackCursor.current & 1)
-        )
+        if (null === current || 0 !== (suspenseStackCursor.current & 1))
           0 === workInProgressRootExitStatus &&
             (workInProgressRootExitStatus = 3);
         else {
@@ -5626,11 +5624,9 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
       null !== current && null === current.memoizedState
         ? !1
         : 0 !== (suspenseContext & 2));
-  JSCompiler_temp
-    ? ((showFallback = !0), (workInProgress.flags &= -129))
-    : (null !== current && null === current.memoizedState) ||
-      !0 === nextProps.unstable_avoidThisFallback ||
-      (suspenseContext |= 1);
+  if (JSCompiler_temp) (showFallback = !0), (workInProgress.flags &= -129);
+  else if (null === current || null !== current.memoizedState)
+    suspenseContext |= 1;
   push(suspenseStackCursor, suspenseContext & 1);
   if (null === current) {
     current = nextProps.children;
@@ -7337,8 +7333,6 @@ function handleError(root, thrownValue$jscomp$0) {
           }
           b: {
             sourceFiber$jscomp$0 = returnFiber;
-            var hasInvisibleParentBoundary =
-              0 !== (suspenseStackCursor.current & 1);
             do {
               var JSCompiler_temp;
               if ((JSCompiler_temp = 13 === sourceFiber$jscomp$0.tag)) {
@@ -7348,12 +7342,6 @@ function handleError(root, thrownValue$jscomp$0) {
                     ? null !== nextState.dehydrated
                       ? !0
                       : !1
-                    : !0 !==
-                      sourceFiber$jscomp$0.memoizedProps
-                        .unstable_avoidThisFallback
-                    ? !0
-                    : hasInvisibleParentBoundary
-                    ? !1
                     : !0;
               }
               if (JSCompiler_temp) {
@@ -7622,7 +7610,7 @@ function commitRootImpl(root, renderPriorityLevel) {
     lanes = root.finishedLanes;
   supportsUserTimingV3 &&
     (markAndClear("--commit-start-" + lanes),
-    markAndClear("--react-version-18.0.0-c1220ebdd-20211123"),
+    markAndClear("--react-version-18.0.0-rc.0-a049aa015-20211213"),
     markAndClear("--profiler-version-1"),
     getLaneLabels(),
     markAndClear("--react-lane-labels-" + laneLabels.join(",")),
@@ -8654,7 +8642,7 @@ function createFiberFromPortal(portal, mode, lanes) {
   };
   return mode;
 }
-function FiberRootNode(containerInfo, tag, hydrate) {
+function FiberRootNode(containerInfo, tag, hydrate, identifierPrefix) {
   this.tag = tag;
   this.containerInfo = containerInfo;
   this.finishedWork = this.pingCache = this.current = this.pendingChildren = null;
@@ -8667,6 +8655,7 @@ function FiberRootNode(containerInfo, tag, hydrate) {
   this.expirationTimes = createLaneMap(-1);
   this.entangledLanes = this.finishedLanes = this.mutableReadLanes = this.expiredLanes = this.pingedLanes = this.suspendedLanes = this.pendingLanes = 0;
   this.entanglements = createLaneMap(0);
+  this.identifierPrefix = identifierPrefix;
   this.passiveEffectDuration = this.effectDuration = 0;
   this.memoizedUpdaters = new Set();
   containerInfo = this.pendingUpdatersLaneMap = [];
@@ -8878,7 +8867,7 @@ var roots = new Map(),
   devToolsConfig$jscomp$inline_1020 = {
     findFiberByHostInstance: getInstanceFromInstance,
     bundleType: 0,
-    version: "18.0.0-c1220ebdd-20211123",
+    version: "18.0.0-rc.0-a049aa015-20211213",
     rendererPackageName: "react-native-renderer",
     rendererConfig: {
       getInspectorDataForViewTag: function() {
@@ -8893,7 +8882,7 @@ var roots = new Map(),
       }.bind(null, findNodeHandle)
     }
   };
-var internals$jscomp$inline_1308 = {
+var internals$jscomp$inline_1307 = {
   bundleType: devToolsConfig$jscomp$inline_1020.bundleType,
   version: devToolsConfig$jscomp$inline_1020.version,
   rendererPackageName: devToolsConfig$jscomp$inline_1020.rendererPackageName,
@@ -8920,19 +8909,19 @@ var internals$jscomp$inline_1308 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.0.0-c1220ebdd-20211123"
+  reconcilerVersion: "18.0.0-rc.0-a049aa015-20211213"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
-  var hook$jscomp$inline_1309 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
+  var hook$jscomp$inline_1308 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
   if (
-    !hook$jscomp$inline_1309.isDisabled &&
-    hook$jscomp$inline_1309.supportsFiber
+    !hook$jscomp$inline_1308.isDisabled &&
+    hook$jscomp$inline_1308.supportsFiber
   )
     try {
-      (rendererID = hook$jscomp$inline_1309.inject(
-        internals$jscomp$inline_1308
+      (rendererID = hook$jscomp$inline_1308.inject(
+        internals$jscomp$inline_1307
       )),
-        (injectedHook = hook$jscomp$inline_1309);
+        (injectedHook = hook$jscomp$inline_1308);
     } catch (err) {}
 }
 exports.createPortal = function(children, containerTag) {
@@ -8972,7 +8961,7 @@ exports.render = function(element, containerTag, callback, concurrentRoot) {
   var root = roots.get(containerTag);
   root ||
     ((root = concurrentRoot ? 1 : 0),
-    (concurrentRoot = new FiberRootNode(containerTag, root, !1)),
+    (concurrentRoot = new FiberRootNode(containerTag, root, !1, "")),
     (root = 1 === root ? 1 : 0),
     isDevToolsPresent && (root |= 2),
     (root = createFiber(3, null, null, root)),
diff --git a/Libraries/Renderer/implementations/ReactNativeRenderer-dev.fb.js b/Libraries/Renderer/implementations/ReactNativeRenderer-dev.fb.js
index 595387b1e2dda8..10b832cd14abc8 100644
--- a/Libraries/Renderer/implementations/ReactNativeRenderer-dev.fb.js
+++ b/Libraries/Renderer/implementations/ReactNativeRenderer-dev.fb.js
@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<8b128574fdea8d0a11f1cf1c1aefe59b>>
+ * @generated SignedSource<<b669579a231fa2a949698a91b71718b9>>
  */
 
 'use strict';
@@ -156,7 +156,7 @@ var invokeGuardedCallbackImpl = invokeGuardedCallbackProd;
       // when we call document.createEvent(). However this can cause confusing
       // errors: https://github.com/facebook/create-react-app/issues/3482
       // So we preemptively throw with a better message instead.
-      if (typeof document === "undefined") {
+      if (typeof document === "undefined" || document === null) {
         throw new Error(
           "The `document` global was defined when React was initialized, but is not " +
             "defined anymore. This can happen in a test environment if a component " +
@@ -3156,6 +3156,7 @@ var enableProfilerCommitHooks = true;
 var enableLazyElements = false;
 var warnAboutStringRefs = false;
 var warnOnSubscriptionInsideStartTransition = false;
+var enableSuspenseAvoidThisFallback = false;
 var enableNewReconciler = false;
 var enableLazyContextPropagation = false;
 
@@ -6241,7 +6242,7 @@ function flushSyncCallbacks() {
   return null;
 }
 
-var ReactVersion = "18.0.0-c1220ebdd-20211123";
+var ReactVersion = "18.0.0-rc.0-a049aa015-20211213";
 
 var SCHEDULING_PROFILER_VERSION = 1;
 
@@ -10681,16 +10682,9 @@ function shouldCaptureSuspense(workInProgress, hasInvisibleParent) {
 
   var props = workInProgress.memoizedProps; // Regular boundaries always capture.
 
-  if (props.unstable_avoidThisFallback !== true) {
+  {
     return true;
   } // If it's a boundary we should avoid, then we prefer to bubble up to the
-  // parent boundary if it is currently invisible.
-
-  if (hasInvisibleParent) {
-    return false;
-  } // If the parent is not able to handle it, we must handle it.
-
-  return true;
 }
 function findFirstSuspended(row) {
   var node = row;
@@ -12439,12 +12433,19 @@ function getIsUpdatingOpaqueValueInRenderPhaseInDEV() {
 
 function mountId() {
   var hook = mountWorkInProgressHook();
+  var root = getWorkInProgressRoot(); // TODO: In Fizz, id generation is specific to each server config. Maybe we
+  // should do this in Fiber, too? Deferring this decision for now because
+  // there's no other place to store the prefix except for an internal field on
+  // the public createRoot object, which the fiber tree does not currently have
+  // a reference to.
+
+  var identifierPrefix = root.identifierPrefix;
   var id;
 
   {
     // Use a lowercase r prefix for client-generated ids.
     var globalClientId = globalClientIdCounter++;
-    id = "r:" + globalClientId.toString(32);
+    id = identifierPrefix + "r:" + globalClientId.toString(32);
   }
 
   hook.memoizedState = id;
@@ -13975,16 +13976,9 @@ function resetSuspendedComponent(sourceFiber, rootRenderLanes) {
 
 function getNearestSuspenseBoundaryToCapture(returnFiber) {
   var node = returnFiber;
-  var hasInvisibleParentBoundary = hasSuspenseContext(
-    suspenseStackCursor.current,
-    InvisibleParentSuspenseContext
-  );
 
   do {
-    if (
-      node.tag === SuspenseComponent &&
-      shouldCaptureSuspense(node, hasInvisibleParentBoundary)
-    ) {
+    if (node.tag === SuspenseComponent && shouldCaptureSuspense(node)) {
       return node;
     } // This boundary already captured during this render. Continue to the next
     // boundary.
@@ -14779,7 +14773,8 @@ function completeWork(current, workInProgress, renderLanes) {
           // should be able to immediately restart from within throwException.
           var hasInvisibleChildContext =
             current === null &&
-            workInProgress.memoizedProps.unstable_avoidThisFallback !== true;
+            (workInProgress.memoizedProps.unstable_avoidThisFallback !== true ||
+              !enableSuspenseAvoidThisFallback);
 
           if (
             hasInvisibleChildContext ||
@@ -16605,7 +16600,7 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
       // Mark this subtree context as having at least one invisible parent that could
       // handle the fallback state.
       // Avoided boundaries are not considered since they cannot handle preferred fallback states.
-      if (nextProps.unstable_avoidThisFallback !== true) {
+      {
         suspenseContext = addSubtreeSuspenseContext(
           suspenseContext,
           InvisibleParentSuspenseContext
@@ -23942,7 +23937,7 @@ function assignFiberPropertiesInDEV(target, source) {
   return target;
 }
 
-function FiberRootNode(containerInfo, tag, hydrate) {
+function FiberRootNode(containerInfo, tag, hydrate, identifierPrefix) {
   this.tag = tag;
   this.containerInfo = containerInfo;
   this.pendingChildren = null;
@@ -23965,6 +23960,7 @@ function FiberRootNode(containerInfo, tag, hydrate) {
   this.finishedLanes = NoLanes;
   this.entangledLanes = NoLanes;
   this.entanglements = createLaneMap(NoLanes);
+  this.identifierPrefix = identifierPrefix;
 
   {
     this.effectDuration = 0;
@@ -23999,9 +23995,10 @@ function createFiberRoot(
   hydrate,
   hydrationCallbacks,
   isStrictMode,
-  concurrentUpdatesByDefaultOverride
+  concurrentUpdatesByDefaultOverride,
+  identifierPrefix
 ) {
-  var root = new FiberRootNode(containerInfo, tag, hydrate);
+  var root = new FiberRootNode(containerInfo, tag, hydrate, identifierPrefix);
   // stateNode is any.
 
   var uninitializedFiber = createHostRootFiber(
@@ -24148,7 +24145,8 @@ function createContainer(
   hydrate,
   hydrationCallbacks,
   isStrictMode,
-  concurrentUpdatesByDefaultOverride
+  concurrentUpdatesByDefaultOverride,
+  identifierPrefix
 ) {
   return createFiberRoot(
     containerInfo,
@@ -24156,7 +24154,8 @@ function createContainer(
     hydrate,
     hydrationCallbacks,
     isStrictMode,
-    concurrentUpdatesByDefaultOverride
+    concurrentUpdatesByDefaultOverride,
+    identifierPrefix
   );
 }
 function updateContainer(element, container, parentComponent, callback) {
@@ -24935,7 +24934,15 @@ function render(element, containerTag, callback) {
   if (!root) {
     // TODO (bvaughn): If we decide to keep the wrapper component,
     // We could create a wrapper for containerTag as well to reduce special casing.
-    root = createContainer(containerTag, LegacyRoot, false, null, false, null);
+    root = createContainer(
+      containerTag,
+      LegacyRoot,
+      false,
+      null,
+      false,
+      null,
+      ""
+    );
     roots.set(containerTag, root);
   }
 
diff --git a/Libraries/Renderer/implementations/ReactNativeRenderer-prod.fb.js b/Libraries/Renderer/implementations/ReactNativeRenderer-prod.fb.js
index 7dcea6842f816e..81d633a6d58cfd 100644
--- a/Libraries/Renderer/implementations/ReactNativeRenderer-prod.fb.js
+++ b/Libraries/Renderer/implementations/ReactNativeRenderer-prod.fb.js
@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<c587a7b3e41dfa079412f1481033cff7>>
+ * @generated SignedSource<<e78790b1fea52e4a08e0efaf4b202318>>
  */
 
 "use strict";
@@ -4047,9 +4047,11 @@ var ContextOnlyDispatcher = {
     },
     useSyncExternalStore: mountSyncExternalStore,
     useId: function() {
-      var hook = mountWorkInProgressHook();
-      var id = "r:" + (globalClientIdCounter++).toString(32);
-      return (hook.memoizedState = id);
+      var hook = mountWorkInProgressHook(),
+        identifierPrefix = workInProgressRoot.identifierPrefix,
+        globalClientId = globalClientIdCounter++;
+      identifierPrefix = identifierPrefix + "r:" + globalClientId.toString(32);
+      return (hook.memoizedState = identifierPrefix);
     },
     unstable_isNewReconciler: !1
   },
@@ -4455,11 +4457,7 @@ function completeWork(current, workInProgress, renderLanes) {
         !renderLanes &&
         ((workInProgress.child.flags |= 8192), 0 !== (workInProgress.mode & 1))
       )
-        if (
-          (null === current &&
-            !0 !== workInProgress.memoizedProps.unstable_avoidThisFallback) ||
-          0 !== (suspenseStackCursor.current & 1)
-        )
+        if (null === current || 0 !== (suspenseStackCursor.current & 1))
           0 === workInProgressRootExitStatus &&
             (workInProgressRootExitStatus = 3);
         else {
@@ -5121,11 +5119,9 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
       null !== current && null === current.memoizedState
         ? !1
         : 0 !== (suspenseContext & 2));
-  JSCompiler_temp
-    ? ((showFallback = !0), (workInProgress.flags &= -129))
-    : (null !== current && null === current.memoizedState) ||
-      !0 === nextProps.unstable_avoidThisFallback ||
-      (suspenseContext |= 1);
+  if (JSCompiler_temp) (showFallback = !0), (workInProgress.flags &= -129);
+  else if (null === current || null !== current.memoizedState)
+    suspenseContext |= 1;
   push(suspenseStackCursor, suspenseContext & 1);
   if (null === current) {
     current = nextProps.children;
@@ -6883,8 +6879,6 @@ function handleError(root$jscomp$0, thrownValue) {
           }
           b: {
             sourceFiber$jscomp$0 = returnFiber;
-            var hasInvisibleParentBoundary =
-              0 !== (suspenseStackCursor.current & 1);
             do {
               var JSCompiler_temp;
               if ((JSCompiler_temp = 13 === sourceFiber$jscomp$0.tag)) {
@@ -6894,12 +6888,6 @@ function handleError(root$jscomp$0, thrownValue) {
                     ? null !== nextState.dehydrated
                       ? !0
                       : !1
-                    : !0 !==
-                      sourceFiber$jscomp$0.memoizedProps
-                        .unstable_avoidThisFallback
-                    ? !0
-                    : hasInvisibleParentBoundary
-                    ? !1
                     : !0;
               }
               if (JSCompiler_temp) {
@@ -8037,7 +8025,7 @@ function createFiberFromPortal(portal, mode, lanes) {
   };
   return mode;
 }
-function FiberRootNode(containerInfo, tag, hydrate) {
+function FiberRootNode(containerInfo, tag, hydrate, identifierPrefix) {
   this.tag = tag;
   this.containerInfo = containerInfo;
   this.finishedWork = this.pingCache = this.current = this.pendingChildren = null;
@@ -8050,6 +8038,7 @@ function FiberRootNode(containerInfo, tag, hydrate) {
   this.expirationTimes = createLaneMap(-1);
   this.entangledLanes = this.finishedLanes = this.mutableReadLanes = this.expiredLanes = this.pingedLanes = this.suspendedLanes = this.pendingLanes = 0;
   this.entanglements = createLaneMap(0);
+  this.identifierPrefix = identifierPrefix;
 }
 function createPortal(children, containerInfo, implementation) {
   var key =
@@ -8263,7 +8252,7 @@ var roots = new Map(),
   devToolsConfig$jscomp$inline_966 = {
     findFiberByHostInstance: getInstanceFromTag,
     bundleType: 0,
-    version: "18.0.0-c1220ebdd-20211123",
+    version: "18.0.0-rc.0-a049aa015-20211213",
     rendererPackageName: "react-native-renderer",
     rendererConfig: {
       getInspectorDataForViewTag: function() {
@@ -8278,7 +8267,7 @@ var roots = new Map(),
       }.bind(null, findNodeHandle)
     }
   };
-var internals$jscomp$inline_1230 = {
+var internals$jscomp$inline_1229 = {
   bundleType: devToolsConfig$jscomp$inline_966.bundleType,
   version: devToolsConfig$jscomp$inline_966.version,
   rendererPackageName: devToolsConfig$jscomp$inline_966.rendererPackageName,
@@ -8305,19 +8294,19 @@ var internals$jscomp$inline_1230 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.0.0-c1220ebdd-20211123"
+  reconcilerVersion: "18.0.0-rc.0-a049aa015-20211213"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
-  var hook$jscomp$inline_1231 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
+  var hook$jscomp$inline_1230 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
   if (
-    !hook$jscomp$inline_1231.isDisabled &&
-    hook$jscomp$inline_1231.supportsFiber
+    !hook$jscomp$inline_1230.isDisabled &&
+    hook$jscomp$inline_1230.supportsFiber
   )
     try {
-      (rendererID = hook$jscomp$inline_1231.inject(
-        internals$jscomp$inline_1230
+      (rendererID = hook$jscomp$inline_1230.inject(
+        internals$jscomp$inline_1229
       )),
-        (injectedHook = hook$jscomp$inline_1231);
+        (injectedHook = hook$jscomp$inline_1230);
     } catch (err) {}
 }
 exports.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED = {
@@ -8363,7 +8352,7 @@ exports.findNodeHandle = findNodeHandle;
 exports.render = function(element, containerTag, callback) {
   var root = roots.get(containerTag);
   if (!root) {
-    root = new FiberRootNode(containerTag, 0, !1);
+    root = new FiberRootNode(containerTag, 0, !1, "");
     var JSCompiler_inline_result = createFiber(3, null, null, 0);
     root.current = JSCompiler_inline_result;
     JSCompiler_inline_result.stateNode = root;
diff --git a/Libraries/Renderer/implementations/ReactNativeRenderer-profiling.fb.js b/Libraries/Renderer/implementations/ReactNativeRenderer-profiling.fb.js
index e4565b6435de2b..550e3b804ecee6 100644
--- a/Libraries/Renderer/implementations/ReactNativeRenderer-profiling.fb.js
+++ b/Libraries/Renderer/implementations/ReactNativeRenderer-profiling.fb.js
@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<d52f24e9901f9340c97ef19e63d99705>>
+ * @generated SignedSource<<62369d90367239846ffa76aa77ae7e87>>
  */
 
 
@@ -4234,9 +4234,11 @@ var ContextOnlyDispatcher = {
     },
     useSyncExternalStore: mountSyncExternalStore,
     useId: function() {
-      var hook = mountWorkInProgressHook();
-      var id = "r:" + (globalClientIdCounter++).toString(32);
-      return (hook.memoizedState = id);
+      var hook = mountWorkInProgressHook(),
+        identifierPrefix = workInProgressRoot.identifierPrefix,
+        globalClientId = globalClientIdCounter++;
+      identifierPrefix = identifierPrefix + "r:" + globalClientId.toString(32);
+      return (hook.memoizedState = identifierPrefix);
     },
     unstable_isNewReconciler: !1
   },
@@ -4742,11 +4744,7 @@ function completeWork(current, workInProgress, renderLanes) {
         !renderLanes &&
         ((workInProgress.child.flags |= 8192), 0 !== (workInProgress.mode & 1))
       )
-        if (
-          (null === current &&
-            !0 !== workInProgress.memoizedProps.unstable_avoidThisFallback) ||
-          0 !== (suspenseStackCursor.current & 1)
-        )
+        if (null === current || 0 !== (suspenseStackCursor.current & 1))
           0 === workInProgressRootExitStatus &&
             (workInProgressRootExitStatus = 3);
         else {
@@ -5426,11 +5424,9 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
       null !== current && null === current.memoizedState
         ? !1
         : 0 !== (suspenseContext & 2));
-  JSCompiler_temp
-    ? ((showFallback = !0), (workInProgress.flags &= -129))
-    : (null !== current && null === current.memoizedState) ||
-      !0 === nextProps.unstable_avoidThisFallback ||
-      (suspenseContext |= 1);
+  if (JSCompiler_temp) (showFallback = !0), (workInProgress.flags &= -129);
+  else if (null === current || null !== current.memoizedState)
+    suspenseContext |= 1;
   push(suspenseStackCursor, suspenseContext & 1);
   if (null === current) {
     current = nextProps.children;
@@ -7430,8 +7426,6 @@ function handleError(root, thrownValue$jscomp$0) {
           }
           b: {
             sourceFiber$jscomp$0 = returnFiber;
-            var hasInvisibleParentBoundary =
-              0 !== (suspenseStackCursor.current & 1);
             do {
               var JSCompiler_temp;
               if ((JSCompiler_temp = 13 === sourceFiber$jscomp$0.tag)) {
@@ -7441,12 +7435,6 @@ function handleError(root, thrownValue$jscomp$0) {
                     ? null !== nextState.dehydrated
                       ? !0
                       : !1
-                    : !0 !==
-                      sourceFiber$jscomp$0.memoizedProps
-                        .unstable_avoidThisFallback
-                    ? !0
-                    : hasInvisibleParentBoundary
-                    ? !1
                     : !0;
               }
               if (JSCompiler_temp) {
@@ -7701,7 +7689,7 @@ function commitRootImpl(root, renderPriorityLevel) {
     lanes = root.finishedLanes;
   supportsUserTimingV3 &&
     (markAndClear("--commit-start-" + lanes),
-    markAndClear("--react-version-18.0.0-c1220ebdd-20211123"),
+    markAndClear("--react-version-18.0.0-rc.0-a049aa015-20211213"),
     markAndClear("--profiler-version-1"),
     getLaneLabels(),
     markAndClear("--react-lane-labels-" + laneLabels.join(",")),
@@ -8726,7 +8714,7 @@ function createFiberFromPortal(portal, mode, lanes) {
   };
   return mode;
 }
-function FiberRootNode(containerInfo, tag, hydrate) {
+function FiberRootNode(containerInfo, tag, hydrate, identifierPrefix) {
   this.tag = tag;
   this.containerInfo = containerInfo;
   this.finishedWork = this.pingCache = this.current = this.pendingChildren = null;
@@ -8739,6 +8727,7 @@ function FiberRootNode(containerInfo, tag, hydrate) {
   this.expirationTimes = createLaneMap(-1);
   this.entangledLanes = this.finishedLanes = this.mutableReadLanes = this.expiredLanes = this.pingedLanes = this.suspendedLanes = this.pendingLanes = 0;
   this.entanglements = createLaneMap(0);
+  this.identifierPrefix = identifierPrefix;
   this.passiveEffectDuration = this.effectDuration = 0;
   this.memoizedUpdaters = new Set();
   containerInfo = this.pendingUpdatersLaneMap = [];
@@ -8957,7 +8946,7 @@ var roots = new Map(),
   devToolsConfig$jscomp$inline_1061 = {
     findFiberByHostInstance: getInstanceFromTag,
     bundleType: 0,
-    version: "18.0.0-c1220ebdd-20211123",
+    version: "18.0.0-rc.0-a049aa015-20211213",
     rendererPackageName: "react-native-renderer",
     rendererConfig: {
       getInspectorDataForViewTag: function() {
@@ -8972,7 +8961,7 @@ var roots = new Map(),
       }.bind(null, findNodeHandle)
     }
   };
-var internals$jscomp$inline_1359 = {
+var internals$jscomp$inline_1358 = {
   bundleType: devToolsConfig$jscomp$inline_1061.bundleType,
   version: devToolsConfig$jscomp$inline_1061.version,
   rendererPackageName: devToolsConfig$jscomp$inline_1061.rendererPackageName,
@@ -8999,19 +8988,19 @@ var internals$jscomp$inline_1359 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.0.0-c1220ebdd-20211123"
+  reconcilerVersion: "18.0.0-rc.0-a049aa015-20211213"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
-  var hook$jscomp$inline_1360 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
+  var hook$jscomp$inline_1359 = __REACT_DEVTOOLS_GLOBAL_HOOK__;
   if (
-    !hook$jscomp$inline_1360.isDisabled &&
-    hook$jscomp$inline_1360.supportsFiber
+    !hook$jscomp$inline_1359.isDisabled &&
+    hook$jscomp$inline_1359.supportsFiber
   )
     try {
-      (rendererID = hook$jscomp$inline_1360.inject(
-        internals$jscomp$inline_1359
+      (rendererID = hook$jscomp$inline_1359.inject(
+        internals$jscomp$inline_1358
       )),
-        (injectedHook = hook$jscomp$inline_1360);
+        (injectedHook = hook$jscomp$inline_1359);
     } catch (err) {}
 }
 exports.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED = {
@@ -9057,7 +9046,7 @@ exports.findNodeHandle = findNodeHandle;
 exports.render = function(element, containerTag, callback) {
   var root = roots.get(containerTag);
   if (!root) {
-    root = new FiberRootNode(containerTag, 0, !1);
+    root = new FiberRootNode(containerTag, 0, !1, "");
     var JSCompiler_inline_result = 0;
     isDevToolsPresent && (JSCompiler_inline_result |= 2);
     JSCompiler_inline_result = createFiber(