diff --git a/CHANGELOG.md b/CHANGELOG.md
index de18616929..90bc4e80e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,12 +15,16 @@ This change log adheres to standards from [Keep a CHANGELOG](https://keepachange
 * [`jsx-key`]: avoid a crash from optional chaining from [#3320][] ([#3327][] @ljharb)
 * [`jsx-key`]: avoid a crash on a non-array node.body from [#3320][] ([#3328][] @ljharb)
 * [`display-name`]: fix false positive for assignment of function returning null ([#3331][] @apbarrero)
+* [`display-name`]: fix identifying `_` as a capital letter ([#3335][] @apbarrero)
 
 ### Changed
 * [Refactor] [`jsx-indent-props`]: improved readability of the checkNodesIndent function ([#3315][] @caroline223)
 * [Tests] [`jsx-indent`], [`jsx-one-expression-per-line`]: add passing test cases ([#3314][] @ROSSROSALES)
 * [Refactor] `boolean-prop-naming`, `jsx-indent`: avoid assigning to arguments ([#3316][] @caroline223)
+* [Docs] `sort-comp`: add class component examples ([#3339][] @maurer2)
 
+[#3339]: https://github.com/jsx-eslint/eslint-plugin-react/pull/3339
+[#3335]: https://github.com/jsx-eslint/eslint-plugin-react/pull/3335
 [#3331]: https://github.com/jsx-eslint/eslint-plugin-react/pull/3331
 [#3328]: https://github.com/jsx-eslint/eslint-plugin-react/issues/3328
 [#3327]: https://github.com/jsx-eslint/eslint-plugin-react/issues/3327
diff --git a/docs/rules/sort-comp.md b/docs/rules/sort-comp.md
index 9eef7c4bfb..974d6d14b9 100644
--- a/docs/rules/sort-comp.md
+++ b/docs/rules/sort-comp.md
@@ -24,6 +24,15 @@ var Hello = createReactClass({
 });
 ```
 
+```jsx
+class Hello extends React.Component {
+  render() {
+    return <div>Hello</div>;
+  }
+  static displayName = 'Hello';
+}
+```
+
 Examples of **correct** code for this rule:
 
 ```jsx
@@ -35,6 +44,15 @@ var Hello = createReactClass({
 });
 ```
 
+```jsx
+class Hello extends React.Component {
+  static displayName = 'Hello';
+  render() {
+    return <div>Hello</div>;
+  }
+}
+```
+
 ## Rule Options
 
 This rule can take one argument to customize the components organisation.
@@ -128,6 +146,16 @@ var Hello = createReactClass({
 });
 ```
 
+```jsx
+class Hello extends React.Component {
+  render() {
+    return <div>Hello</div>;
+  }
+  onClick = this.onClick.bind(this);
+  onClick() {}
+}
+```
+
 Examples of **correct** code for this rule, with the above configuration:
 
 ```jsx
@@ -139,6 +167,16 @@ var Hello = createReactClass({
 });
 ```
 
+```jsx
+class Hello extends React.Component {
+  onClick = this.onClick.bind(this);
+  onClick() {}
+  render() {
+    return <div>Hello</div>;
+  }
+}
+```
+
 If you want to split your `render` method into smaller ones and keep them just before render:
 
 ```js
@@ -170,6 +208,17 @@ var Hello = createReactClass({
 });
 ```
 
+```jsx
+class Hello extends React.Component {
+  renderButton = () => {}
+  onClick = this.onClick.bind(this);
+  onClick() {}
+  render() {
+    return <div>Hello</div>;
+  }
+}
+```
+
 Examples of **correct** code for this rule, with the above configuration:
 
 ```jsx
@@ -182,6 +231,17 @@ var Hello = createReactClass({
 });
 ```
 
+```jsx
+class Hello extends React.Component {
+  onClick = this.onClick.bind(this);
+  onClick() {}
+  renderButton = () => {}
+  render() {
+    return <div>Hello</div>;
+  }
+}
+```
+
 If you want to flow annotations to be at the top:
 
 ```js
diff --git a/lib/util/isFirstLetterCapitalized.js b/lib/util/isFirstLetterCapitalized.js
index f487489b65..819edc8860 100644
--- a/lib/util/isFirstLetterCapitalized.js
+++ b/lib/util/isFirstLetterCapitalized.js
@@ -6,7 +6,7 @@
  * @returns {Boolean} True if first letter is capitalized.
  */
 function isFirstLetterCapitalized(word) {
-  if (!word) {
+  if (!word || word.charAt(0) === '_') {
     return false;
   }
   const firstLetter = word.charAt(0);
diff --git a/tests/helpers/parsers.js b/tests/helpers/parsers.js
index b0e0a7af9c..de7dcbc8e6 100644
--- a/tests/helpers/parsers.js
+++ b/tests/helpers/parsers.js
@@ -2,6 +2,7 @@
 
 const path = require('path');
 const semver = require('semver');
+const entries = require('object.entries');
 const version = require('eslint/package.json').version;
 const flatMap = require('array.prototype.flatmap');
 const tsParserVersion = require('@typescript-eslint/parser/package.json').version;
@@ -10,6 +11,25 @@ const disableNewTS = semver.satisfies(tsParserVersion, '>= 4.1') // this rule is
   ? (x) => Object.assign({}, x, { features: [].concat(x.features, 'no-ts-new') })
   : (x) => x;
 
+function minEcmaVersion(features, parserOptions) {
+  const minEcmaVersionForFeatures = {
+    'class fields': 2022,
+    'optional chaining': 2020,
+  };
+  const result = Math.max.apply(
+    Math,
+    [].concat(
+      (parserOptions && parserOptions.ecmaVersion) || [],
+      flatMap(entries(minEcmaVersionForFeatures), (entry) => {
+        const f = entry[0];
+        const y = entry[1];
+        return features.has(f) ? y : [];
+      })
+    ).map((y) => (y > 5 && y < 2015 ? y + 2009 : y)) // normalize editions to years
+  );
+  return Number.isFinite(result) ? result : undefined;
+}
+
 const NODE_MODULES = '../../node_modules';
 
 const parsers = {
@@ -58,7 +78,7 @@ const parsers = {
       const features = new Set([].concat(test.features || []));
       delete test.features;
 
-      const es = features.has('class fields') ? 2022 : (features.has('optional chaining') ? 2020 : (test.parserOptions && test.parserOptions.ecmaVersion) || undefined); // eslint-disable-line no-nested-ternary
+      const es = minEcmaVersion(features, test.parserOptions);
 
       function addComment(testObject, parser) {
         const extras = [].concat(
@@ -133,10 +153,8 @@ const parsers = {
 
       return [].concat(
         skipBase ? [] : addComment(
-          Object.assign({}, test, typeof es !== 'undefined' && {
-            parserOptions: Object.assign({}, test.parserOptions, {
-              ecmaVersion: Math.max((test.parserOptions && test.parserOptions.ecmaVersion) || 0, es),
-            }),
+          Object.assign({}, test, typeof es === 'number' && {
+            parserOptions: Object.assign({}, test.parserOptions, { ecmaVersion: es }),
           }),
           'default'
         ),
diff --git a/tests/lib/rules/display-name.js b/tests/lib/rules/display-name.js
index 39bdb59cb5..ba4b9181fe 100644
--- a/tests/lib/rules/display-name.js
+++ b/tests/lib/rules/display-name.js
@@ -597,6 +597,24 @@ ruleTester.run('display-name', rule, {
           return f(a);
         };`,
     },
+    {
+      // issue #3334
+      code: `
+        obj._property = (a) => {
+          if (a == null) return null;
+          return f(a);
+        };
+      `,
+    },
+    {
+      // issue #3334
+      code: `
+        _variable = (a) => {
+          if (a == null) return null;
+          return f(a);
+        };
+      `,
+    },
     {
       // issue #3303
       code: `
diff --git a/tests/util/isFirstLetterCapitalized.js b/tests/util/isFirstLetterCapitalized.js
index 5ccbfea68e..85bdffd1bc 100644
--- a/tests/util/isFirstLetterCapitalized.js
+++ b/tests/util/isFirstLetterCapitalized.js
@@ -14,6 +14,8 @@ describe('isFirstLetterCapitalized', () => {
   it('should return false for uncapitalized string', () => {
     assert.equal(isFirstLetterCapitalized('isCapitalized'), false);
     assert.equal(isFirstLetterCapitalized('lowercase'), false);
+    assert.equal(isFirstLetterCapitalized('_startsWithUnderscore'), false);
+    assert.equal(isFirstLetterCapitalized('_StartsWithUnderscore'), false);
   });
 
   it('should return true for capitalized string', () => {