How to reproduce:
1. Create and open a new URP project
2. Wait for the Asset Import to finish
3. Open the Task Manager and search for “Unity“
4. Quit the Editor
5. Observe the Unity Editor instance in the Task Manager

Actual result: All “Unity Editor” and related processes are ended more slowly (~5s for all background processes to end)
Expected result: All “Unity Editor” and related processes are ended quickly (<2s for all background processes to end)

Reproducible in: 6000.3.0a1, 6000.3.11f1, 6000.4.0f1, 6000.5.0a9, 6000.6.0a1
Not reproducible in: 6000.0.71f1, 6000.2.0b2 (2bdac9ac0d74)

Reproduced on: Windows 11 Pro (25H2), macOS 15.9.3 (M1 Max)
Not reproduced on: No other environment tested

Note: Starting in 6000.3.0a2, the Task Manager reports 3 more simultaneous “sub-processes” working alongside the main Editor instance. It’s unknown if they’re related to the described behavior