Two questions for someone not experiencing crashes:
- Do you use Fast-User switching?
- Are you using Microsoft Office 365 (installs OneDrive)?
We have about one spontaneous restart every 4-5 days. Far higher than on my older Intel Air, but better than many here. We did use migration assistant to go from High Sierra. I've seen improvement after reinstalling macOS and one of the recent Big Sur updates. This is still not an acceptable behavior though.
The last step is a full wipe and reinstall -- but that's at least a full day of my life. At my age I don't have that many life days to burn!
I'm going to give it at least one more macOS/firmware update before going there.