[0.83.1] useColorScheme returns unspecified when state updates

Description

I’m using useColorScheme to manage theming in my app.

The app has three theme options: System, Dark, and Light.

• When System is selected, I call Appearance.setColorScheme('unspecified').
• When Dark is selected, I call Appearance.setColorScheme('dark').
• When Light is selected, I call Appearance.setColorScheme('light').

If the system theme is dark and I call Appearance.setColorScheme('unspecified'), useColorScheme correctly returns dark.

However, if I update a state during the same button click, useColorScheme starts returning unspecified instead.

Steps to reproduce

1. Change color schemes by clicking buttons
2. It should work
3. Enable state change by clicking enable state change button
4. Change color schemes by clicking buttons
5. It returns unspecified when you change from system color (dark or light) to system

React Native Version

0.83.1

Affected Platforms

Runtime - iOS

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

System:
  OS: macOS 26.2
  CPU: (8) arm64 Apple M1 Pro
  Memory: 108.17 MB / 16.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 22.19.0
    path: /Users/aykutsaki/.nvm/versions/node/v22.19.0/bin/node
  Yarn:
    version: 1.22.15
    path: /opt/homebrew/bin/yarn
  npm:
    version: 10.9.3
    path: /Users/aykutsaki/.nvm/versions/node/v22.19.0/bin/npm
  Watchman:
    version: 2025.05.26.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.2
      - iOS 26.2
      - macOS 26.2
      - tvOS 26.2
      - visionOS 26.2
      - watchOS 26.2
  Android SDK:
    API Levels:
      - "31"
      - "35"
      - "36"
    Build Tools:
      - 35.0.0
      - 36.0.0
    System Images:
      - android-35 | Google Play ARM 64 v8a
      - android-36 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2025.2 AI-252.25557.131.2521.14344949
  Xcode:
    version: 26.2/17C52
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.9
    path: /Users/aykutsaki/.jenv/shims/javac
  Ruby:
    version: 3.2.2
    path: /Users/aykutsaki/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.0.0
    wanted: 20.0.0
  react:
    installed: 19.2.0
    wanted: 19.2.0
  react-native:
    installed: 0.83.1
    wanted: 0.83.1
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

No crash

MANDATORY Reproducer

https://github.com/AuroPick/color-scheme-unspecified

Screenshots and Videos

https://github.com/user-attachments/assets/78519563-4a32-44c0-8bf3-2a997bff4f57

Bắt đầu bằng cách chạy trình tái hiện bắt buộc tại https://github.com/AuroPick/color-scheme-unspecified trên iOS và quan sát useColorScheme cùng với Appearance.setColorScheme. Theo dõi đường đi của việc cập nhật trạng thái và xác minh rằng khi chọn lại System, hệ thống báo theme hệ thống đã được phân giải thay vì unspecified, kể cả khi một trạng thái khác cũng thay đổi trong cùng lần nhấp nút.