Hi Atlau,
I'd never had that problem until I saw this post yesterday. since then it happened about 8 times yesterday evening. There was a windows update that updated the environment came out a couple of days ago that I hadn't installed yet. Installed it lastnight to see if it would help but still got the issue. I think it's the steam overlay is the problem though. Using the Steam VR environment inside Steam to run the game I think just is consuming too many resources.
I wonder is there a way to run the game directly in the WMR environment and bypass the steam one? I'm not sure, but it's infuriating when you're in the middle of a dive and it happens or in the middle of anything really.
I'll keep an eye on this post, see if anyone finds a solution.
Dread