Reproduction steps:
1. Open the attached project "Case_1382050.zip" and load Scene "SampleScene"
2. In the Menu Bar go to File -> Build Settings and change Build Target to "iOS" or "Android"
3. In the Hierarchy select "Directional Light"
4. Observe the Game View
5. In the Inspector use the Slider to change the value of "Strength"

Expected result: No shadows appear on the Meshes
Actual result: Certain values of "Strength" create either white or black shadows on the Meshes

Reproducible with: 2020.3.23f1, 2021.2.3f1, 2022.1.0a6, 2022.1.0a15
Not reproducible with: 2019.4.32f1, 2022.1.0a5

Reproduced with:
- MacOS Editor with Build Target iOS (Metal)
- MacOS Editor with Build Target Android (Metal)
- MacOS Editor with Build Target tvOS (Metal)

Does not reproduce with:
- Windows Editor with Build Target Windows
- Windows Editor with Build Target iOS
- MacOS Editor with Build Target iOS (Open GLCore)
- MacOS Editor with Build Target macOS (Open GLCore)
- Player with Build Target iOS

Notes:
- Issue is also reproducible in Scene View