Has anyone with the issue tried this update by chance (or made sure it's installed?)? https://www.bleepingcomputer.com/news/microsoft/windows-10-kb5000842-cumulative-update-fixes-freezing-issues/
I had the freezing problem when I had moved forward from 2004 to 20H2 and then I rolled back to 2004 and the problem went away - I'm still on 2004 and I won't install a new version until 21H2 later this year, but I am continuing to monitor this thread as this is a very concerning problem. Hoping an actual solution is found at some point since some people who have now tried 21H1 are still having some issues as well.
EDIT - Also has anyone tried disabling "Hardware Accelerated GPU scheduling"? I saw one post on reddit where someone had mentioned that resolving system freezes for them. So just something to try. Since I am not currently having the issue with v2004 I can't test any of this stuff.