How to reproduce:
1. Open the attached 'Unity UAAL ScreenOrientation Bug Report.zip' project
2. Switch Platform to iOS in Build Settings
3. Build for iOS and open the Xcode project
4. Generate a new Xcode workspace
5. Add NativeiOSApp and built Xcode project to the created workspace
6. Mark Unity-iPhone / Libraries / Plugins / iOS / NativeCallProxy.h as public in Target Membership section of the right sidebar
7. Change Target Membership for Unity-iPhone/Data folder to UnityFramework
8. Select NativeiOSApp scheme and run it
9. In the launched app click the 'Init' button
10. Hold the device in landscape right mode (you can modes in the debugger)
11. Rotate the device in portrait mode
12. Observe the debugger

Expected result: Screen.orientation method returns portrait
Actual result: Screen.orientation method returns portrait upside down

Reproducible with:
iPhone 8+ (iOS 12.0)
iPhone XR (iOS 13.4.1)
iPad 9.7’ 6th gen (iOS 14.2)

Reproducible with: 2019.4.13f1, 2020.1.9f1, 2020.2.0b7, 2021.1.0a1
Could not test with: 2018.4.29f1 UAAL is not supported

Notes:
- Detailed steps with screenshots of how to reproduce the issue is here: https://forum.unity.com/threads/integration-unity-as-a-library-in-native-ios-app.685219/
- Attached screenshot of the issue