Last FlatList item component re-mounted when adding new elements at the beginning of the list

Description

Each time a new component is added at the beginning or in the middle of the list, the last component (the one that was added first) re-mounts. I've noticed that when a new component is added to the list, a spacer component is created and it always replaces last component in that list, even if new components are added at the beginning or in the middle of the list. This makes last item to completely re-mount. This problem only occurs when the initialNumToRender is exceeded.

Steps to reproduce

1. Run repro from linked snack.
2. Press add button multiple times (at least 4).
3. You will see in the terminal that after reaching initialNumToRender last item is unmounted.

React Native Version

0.74.1

Affected Platforms

Runtime - Android, Runtime - iOS

Output of npx react-native info

System:
  OS: macOS 14.4.1
  CPU: (11) arm64 Apple M3 Pro
  Memory: 110.58 MB / 18.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 21.7.3
    path: /opt/homebrew/bin/node
  Yarn:
    version: 4.1.1
    path: /opt/homebrew/bin/yarn
  npm:
    version: 10.5.0
    path: /opt/homebrew/bin/npm
  Watchman:
    version: 2024.04.08.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.14.3
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 23.5
      - iOS 17.5
      - macOS 14.5
      - tvOS 17.5
      - visionOS 1.2
      - watchOS 10.5
  Android SDK:
    API Levels:
      - "31"
      - "34"
    Build Tools:
      - 30.0.3
      - 33.0.1
      - 34.0.0
    System Images:
      - android-34 | Google APIs ARM 64 v8a
      - android-TiramisuPrivacySandbox | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2023.2 AI-232.10300.40.2321.11668458
  Xcode:
    version: 15.4/15F31d
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.10
    path: /usr/bin/javac
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.2.0
    wanted: 18.2.0
  react-native:
    installed: 0.74.0
    wanted: 0.74.0
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false

Stacktrace or Logs

-

Reproducer

https://snack.expo.dev/@exploifswm/flat-list-item-re-mount

Screenshots and Videos

No response

首先使用 React Native 0.74.1 运行链接的 Expo Snack 复现器，并检查列表超过 initialNumToRender 后 FlatList 的行为。在 Android 和 iOS 上分别跟踪从开头或中间插入新元素时哪个列表项会被 unmounted。完成标准是添加项后不再 remount 最后一个现有项。