fix: Older state events overwrite newer ones on fetching history

lib/src/client.dart

@@ -2650,8 +2650,19 @@ class Client extends MatrixApi {
       if (syncRoomUpdate is JoinedRoomUpdate) {
         final state = syncRoomUpdate.state;
 
+        // If we are receiving states when fetching history we need to check if
+        // we are not overwriting a newer state.
+        if (direction == Direction.b) {
+          await room.postLoad();
+          state?.removeWhere((state) {
+            final existingState =
+                room.getState(state.type, state.stateKey ?? '');
+            if (existingState is! MatrixEvent) return false;
+            return existingState.originServerTs.isAfter(state.originServerTs);
+          });
+        }
+
         if (state != null && state.isNotEmpty) {
-          // TODO: This method seems to be comperatively slow for some updates
           await _handleRoomEvents(
             room,
             state,