[Android] - Can't access ShadowNode in FlatList with horizontal prop

Description

I've found a discrepancy between Android and iOS platforms.
When the horizontal prop is set, the ref returned during unmount has a nullable NativeState property which breaks ShadowNode cleanup required by Unistyles.

How I access the NativeState for FlatList components:

ref?.getScrollResponder?.()?.getNativeScrollRef?.()?.__internalInstanceHandle?.stateNode?.node

Link

and then in C++:

ShadowNode::Shared shadowNode = shadowNodeFromValue(rt, args[0]); // args[0] is jsi::Value with NativeState

Desired behaviour:
I should be able to access ShadowNode during cleanup to perform own cleanups as in any other component or without horizontal prop.

Steps to reproduce

1. Install the provided repro
2. Run the app on Android and open the debugger to view console.log output
3. You should see two logs:

   Mount
   NativeState: ✅
   

4. Tap the Reload button
5. Notice that NativeState is no longer present:

   Unmount
   NativeState: ❌
   

6. Run the app on iOS and open the debugger to view console.log output
7. Verify that NativeState is present in both the mount and unmount phases
8. Comment out the horizontal prop
9. Verify that NativeState is present in both the mount and unmount phases on both iOS and Android

React Native Version

0.79.2

Affected Platforms

Runtime - Android

Areas

Fabric - The New Renderer

Output of npx @react-native-community/cli info

System:
  OS: macOS 15.3.2
  CPU: (12) arm64 Apple M3 Pro
  Memory: 2.15 GB / 36.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 23.5.0
    path: /opt/homebrew/bin/node
  Yarn:
    version: 1.22.22
    path: /opt/homebrew/bin/yarn
  npm:
    version: 10.9.2
    path: /opt/homebrew/bin/npm
  Watchman:
    version: 2024.12.02.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 24.4
      - iOS 18.4
      - macOS 15.4
      - tvOS 18.4
      - visionOS 2.4
      - watchOS 11.4
  Android SDK:
    API Levels:
      - "23"
      - "28"
      - "29"
      - "30"
      - "33"
      - "34"
      - "35"
    Build Tools:
      - 30.0.3
      - 34.0.0
      - 35.0.0
    System Images:
      - android-23 | ARM 64 v8a
      - android-24 | Google APIs ARM 64 v8a
      - android-26 | Google APIs ARM 64 v8a
      - android-28 | ARM 64 v8a
      - android-29 | ARM 64 v8a
      - android-30 | ARM 64 v8a
      - android-30 | Google APIs ARM 64 v8a
      - android-34 | Android TV ARM 64 v8a
      - android-34 | ARM 64 v8a
      - android-34 | Google APIs ARM 64 v8a
      - android-35 | Google APIs ARM 64 v8a
      - android-35 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2024.3 AI-243.25659.59.2432.13404313
  Xcode:
    version: 16.3/16E140
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.11
    path: /usr/bin/javac
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 18.0.0
    wanted: 18.0.0
  react:
    installed: 19.0.0
    wanted: 19.0.0
  react-native:
    installed: 0.79.2
    wanted: 0.79.2
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true

Stacktrace or Logs

No crash

MANDATORY Reproducer

https://github.com/jpudysz/react-native-horizontal-flatlist-repro

Screenshots and Videos

Android + horizontal prop

Android + no horizontal prop

iOS + horizontal prop

iOS + no horizontal prop

Start with the mandatory reproducer and compare the Android and iOS logs for FlatList with and without the horizontal prop. Trace the Fabric ShadowNode cleanup path around NativeState and the Android implementation, using the reported React Native 0.79.2 setup. Done means NativeState remains available during Android unmount cleanup for horizontal FlatList, matching the other cases.