Repro steps:
1. Open the attached project "Unity Screen Orientation Android"
2. Build and Run on Android
3. After the app launches rotate the device to landscape
4. Press "Button Portrait 2" on the screen

Expected: Orientation switches to portrait
Actual: Orientation stays in landscape

Reproducible with: 2020.1.0a2, 2020.3.7f1, 2021.1.6f1, 2021.2.0a17
Not reproducible with: 019.4.24f1, 2020.1.0a1

Tested and reproduced on these devices:
N/A, Google Pixel 3 XL (Pixel 3 XL), Android 11, CPU: NOT FOUND, GPU: Adreno (TM) 630
N/A, Huawei - (NOH-NX9), Android 10, CPU: NOT FOUND, GPU: Mali-G78
VLNQA00001, Google Pixel 2 (Pixel 2), Android 11, CPU: Snapdragon 835 MSM8998, GPU: Adreno (TM) 540
VLNQA00316, Samsung Galaxy Note10 (SM-N970F), Android 9, CPU: Exynos 9 Series 9825, GPU: Mali-G76

Doesn't reproduce on
iPhone 11 (iOS 13.5)

Notes:
- Couldn't test 2018.4