Unmounting list header component while applying maintainVisibleContentPosition to flatlist renders white space in place of header compoent on Ios

Description

If a flatlist with a maintainVisibleContentPosition prop set has a header list component that is unmounted then the header component unmounts but the list does not scroll to the first element and instead renders white space.

Here is the source code also available as snack:

import React, {useState} from 'react';
import {
  SafeAreaView,
  View,
  FlatList,
  StyleSheet,
  Text,
  StatusBar,
  Button,
} from 'react-native';

type ItemProps = {title: string};

const Item = ({title}: ItemProps) => (
  <View style={styles.item}>
    <Text style={styles.title}>{title}</Text>
  </View>
);

const App = () => {
  const [isHeaderShown, setIsHeaderShown] = useState(true);
  return (
    <SafeAreaView style={styles.container}>
      <FlatList
        maintainVisibleContentPosition={{
          minIndexForVisible: 0,
          autoscrollToTopThreshold: 0,
        }}
        ListHeaderComponent={
          isHeaderShown ? (
            <View style={{padding: 128, backgroundColor: 'red'}} />
          ) : null
        }
        data={Array.from({length: 30})
          .fill(0)
          .map((_, index) => `Item ${index}`)}
        renderItem={({item}) => <Item title={item} />}
      />
      <Button
        title="press me"
        onPress={() => {
          setIsHeaderShown(prev => !prev);
        }}
      />
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    marginTop: StatusBar.currentHeight || 0,
  },
  item: {
    backgroundColor: '#f9c2ff',
    padding: 20,
    marginVertical: 8,
    marginHorizontal: 16,
  },
  title: {
    fontSize: 32,
  },
});

export default App;

Steps to reproduce

1. click on the press me button and notice how there is white space on ios and the list does not scroll, but works fine on android

React Native Version

0.73.4

Affected Platforms

Runtime - iOS

Output of npx react-native info

System:
  OS: macOS 14.1.2
  CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
  Memory: 2.57 GB / 16.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 18.17.1
    path: ~/.nvm/versions/node/v18.17.1/bin/node
  Yarn:
    version: 1.22.19
    path: ~/.nvm/versions/node/v18.17.1/bin/yarn
  npm:
    version: 9.6.7
    path: ~/.nvm/versions/node/v18.17.1/bin/npm
  Watchman:
    version: 2024.01.22.00
    path: /usr/local/bin/watchman
Managers:
  CocoaPods:
    version: 1.15.0
    path: /Users/ramiel/.rbenv/shims/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 23.2
      - iOS 17.2
      - macOS 14.2
      - tvOS 17.2
      - visionOS 1.0
      - watchOS 10.2
  Android SDK: Not Found
IDEs:
  Android Studio: 2023.1 AI-231.9392.1.2311.11076708
  Xcode:
    version: 15.2/15C500b
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 11.0.15
    path: /usr/local/opt/openjdk@11/bin/javac
  Ruby:
    version: 2.7.6
    path: /Users/ramiel/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.2.0
    wanted: 18.2.0
  react-native:
    installed: 0.73.4
    wanted: 0.73.4
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false

### Stacktrace or Logs

```text
No Stacktrace or Logs

Reproducer

https://snack.expo.dev/@ramiel99/maintainvisiblecontentposition-header-top

Screenshots and Videos

https://github.com/facebook/react-native/assets/80689446/c563b30a-b61d-4822-9e77-0820b25756a7

リンクされた Snack の再現例と、iOS における FlatList maintainVisibleContentPosition の挙動から始めます。条件付きでアンマウントされる ListHeaderComponent に対する iOS の処理を追跡し、その後、header の切り替えによって空白が取り除かれ、Android の挙動にリグレッションを起こすことなく最初の項目までスクロールすることを確認します。