Repro steps:

1. Import the attached package and open the repro scene.
2. Enter play mode
3. Remove focus from Unity for a few min. (sometimes happens within 2-3 min, but give it 10 to be really safe)
4. Observe how after a while the rendering has paused and console errors are spamming the console.

Expected outcome:
- No errors

Notes:
- Happens also on 2021.1.0b1.1725