[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

从 https://github.com/Regina-v/rn-ios26-switch-custom-color-bug 中的必需复现项目开始，按照报告中的说明，在 iOS 26 上复现 switch 的行为，并与 iOS 18 进行比较。跟踪 React Native 的 switch 实现，并验证离开应用后再返回时自定义 thumb 颜色仍然保留；当报告的颜色丢失问题不再发生时，即视为完成。