How to reproduce:
1. Extract and open the attached “IN-112321.zip” project
2. Open the Assets/Scenes/OutdoorScene.unity Scene
3. Enter Play mode
4. In the Game View, observe the gradual FPS decrease (in my case, from 250FPS to 150FPS) over a 10-minute period
5. Exit out of Play mode
6. Enter Play mode
7. Observe the FPS counter

Expected result: The FPS should return to the level observed when Play mode was first entered
Actual result: The FPS remains low and does not recover, staying at the degraded level seen after 10 minutes in Play mode

Reproducible with: 6000.0.11f1, 6000.0.57f1, 6000.2.3f1, 6000.3.0b1
Could not test with: 2023.1.0a1, 6000.0.10f1 (413673acabac) (Errors due to package compatibility. Attempting to fix the errors severely affected the project, leading to more compilation errors)

Reproducible on: Windows 11
Not reproducible on: MacOS 15.6 (Silicon)

Workarounds:
- Moving the Editor screen to a different monitor and then back returns the FPS to the level observed when Play mode was first entered
- Restarting the Editor returns the FPS to the level observed when Play mode was first entered