iOS Fabric: `display: none` silently destroys host-component, instead of just hiding or removing it

Description

Hi, Ioannis here from Margelo.

While migrating a client's app to the new architecture, we noticed that on iOS fabric, whenever a fabric component under Suspense get's suspended (thus display:none was set), our native view components were unmounted (removed and deleted - not just hidden but actually deallocated) and that resulted on their state being lost.

This seems to be a change in behavior to the old arch, where display: none would merely hide the view.

I did a poll among my RN colleagues, and no one expected that the view would be deleted on display: none especially given that you apply that style with the intention to bring the view back after a moment.

Furthermore, the behavior is what we'd expect on Android, where fabric choses to just hide the views (setVisibility(GONE)).

I was wondered if this was added intentionally back then? If so, I think i'd prefer to have a way to either opt-in/out of this behavior (see my PR).

Steps to reproduce

1. Clone https://github.com/SudoPlz/reproducer-react-native
2. cd ReproducerApp && yarn install && cd ios && pod install && cd ..
3. yarn ios
4. Tap "Set red" → red. Tap "Toggle display" off → gone. Tap "Toggle display" on → reappears WHITE (Command-set state lost).
5. Notice dealloc being called

React Native Version

0.85.2

Affected Platforms

Runtime - iOS

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

System:
  OS: macOS 26.4.1
  CPU: (14) arm64 Apple M4 Pro
  Memory: 1.61 GB / 48.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 22.14.0
    path: /nix/store/04fc23dsflkxl4s9p6lkigia1hq3vjp2-nodejs-22.14.0/bin/node
  Yarn:
    version: 1.22.19
    path: /Users/sudoplz/.nix-profile/bin/yarn
  npm:
    version: 10.9.2
    path: /nix/store/04fc23dsflkxl4s9p6lkigia1hq3vjp2-nodejs-22.14.0/bin/npm
  Watchman:
    version: 2024.03.11.00
    path: /Users/sudoplz/.nix-profile/bin/watchman
Managers:
  CocoaPods:
    version: 1.15.2
    path: /Users/sudoplz/.nix-profile/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.2
      - iOS 26.2
      - macOS 26.2
      - tvOS 26.2
      - visionOS 26.2
      - watchOS 26.2
IDEs:
  Xcode:
    version: 26.2/17C52
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 21.0.7
  Ruby:
    version: 3.4.4
    path: /Users/sudoplz/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.1.0
    wanted: 20.1.0
  react:
    installed: 19.2.3
    wanted: 19.2.3
  react-native:
    installed: 0.85.2
    wanted: 0.85.2
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

None — not a crash. The next render after display flips back simply shows a freshly-constructed host view with default state.

Reproducer

https://github.com/SudoPlz/reproducer-react-native

Screenshots and Videos

https://github.com/user-attachments/assets/bc7f1193-87ec-4c3b-b0d2-45947e32faa9

Commencez par packages/react-native/ReactCommon/react/renderer/mounting/Differentiator.cpp aux lignes indiquées, puis exécutez l’exemple SudoPlz/reproducer-react-native sur iOS Fabric. Suivez le chemin display:none et observez dealloc ainsi que la perte d’état lorsque display est basculé. C’est terminé lorsque le comportement iOS attendu est établi et que le basculement de display n’entraîne plus de perte inattendue de l’état de la vue hôte.