Question Long hangs entering and exiting playmode only on work PC

Hello, I need some help diagnosing this issue which is very disruptive to my workflow. I work on a HoloLens 2 project in Unity 2021.1. Recently I started experiencing long hangs (20s - 2 min) every time I exit playmode and most times when entering playmode but only on my work PC. When this happens the editor becomes completely unresponsive with 0% CPU utilization in Task Manager. Profiler shows a long hang of EditorLoop on the last frame (attachment):

Sometimes a popup with Application.UpdateScene appears during the hang. Sometimes it also happens when opening/changing some inspectors.

It happens on all Hololens projects that have the Mixed Reality Toolkit (MRTK) added to the scene. I haven't updated MRTK since before the hang started happening.

I've tried:
- cloning the project from scratch on both PCs
- reinstalling/updating the Unity Editor (I was using some 2021.1.1x version when it first happened)
- making sure Unity build settings and preferences are the same on both PCs
- updating GPU drivers
- adding git folder to Windows Defender
- disabling Windows Defender realtime protection

I'm using:
- Unity 2021.1.28f1
- MRTK 2.7.2
- OpenXR Plugin 1.2.8
- Mixed Reality OpenXR Plugin 1.1.2

I can't update to Unity 2021.2 because I'm waiting for a fix in MRTK for some errors that were introduced with it.

On my significantly slower home PC everything works fine:

Home PC: AMD 3600, 16 GB @ 3200 MHz, 2070S, project on HDD, Unity Editor on M.2 SSD
Work PC: AMD 5800X, 16 GB @ 3600 MHz, 3060Ti, project & Unity Editor on M.2 SSD