[iOS 26] Switch with custom thumb color is losing color when coming back to app

Description

Using iOS 26, when you give a switch custom thumb colors, go to another app, come back to your app, then the custom colors are lost.

Steps to reproduce

1. Install the application on iOS 26.
2. Enable one of the toggles.
3. Switch app and come back.
4. Thumbs of switches which used to have a custom thumb color are white.

React Native Version

0.81.4

Affected Platforms

Runtime - iOS 26

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

System:
  OS: macOS 15.6.1
  CPU: (12) arm64 Apple M2 Pro
  Memory: 129.11 MB / 32.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 22.18.0
    path: ~/.nvm/versions/node/v22.18.0/bin/node
  Yarn:
    version: 4.6.0
    path: ~/.nvm/versions/node/v22.18.0/bin/yarn
  npm:
    version: 10.9.3
    path: ~/.nvm/versions/node/v22.18.0/bin/npm
  Watchman:
    version: 2025.09.15.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.15.2
    path: /Users/regina/.gem/ruby/3.2.2/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.0
      - iOS 26.0
      - macOS 26.0
      - tvOS 26.0
      - visionOS 26.0
      - watchOS 26.0
  Android SDK: Not Found
IDEs:
  Android Studio: 2024.3 AI-243.24978.46.2431.13363775
  Xcode:
    version: 26.0/17A324
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.13
    path: /usr/bin/javac
  Ruby:
    version: 3.2.2
    path: /Users/regina/.rubies/ruby-3.2.2/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.0.0
    wanted: 20.0.0
  react:
    installed: 19.1.0
    wanted: 19.1.0
  react-native:
    installed: 0.81.4
    wanted: 0.81.4
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

N/A

MANDATORY Reproducer

https://github.com/Regina-v/rn-ios26-switch-custom-color-bug

Screenshots and Videos

Screen record iOS 26: https://github.com/user-attachments/assets/33e01479-e9f7-4e29-9719-e9128a2ce1b9

Screen record iOS 18: https://github.com/user-attachments/assets/7b67f017-3ecd-46e7-accf-4b2773026c25

Commencez par le reproducteur obligatoire à l’adresse https://github.com/Regina-v/rn-ios26-switch-custom-color-bug et reproduisez le comportement du switch sur iOS 26, en le comparant à iOS 18 comme indiqué dans le rapport. Suivez l’implémentation du switch de React Native et vérifiez que les couleurs personnalisées du thumb sont conservées après avoir quitté l’application et y être revenu ; le travail est terminé lorsque la perte de couleur signalée ne se produit plus.