I've been wrestling with this for months as well, and I've only now found this forum that is discussing it. I thought I was going crazy. I've even done a complete uninstall and reinstall of Windows 365, but it's changed nothing. This isn't just costing me money and wasted effort—it's destroying my confidence as a professional editor. I no longer have control over the document. I have zero confidence I'm not actually introducing errors at this point.
It is beyond belief that something like this could happen this far down the road in an application's existence. Stop making "improvements" that introduce horrible glitches that make the app almost unusable.
Are you trying to force everyone to Google Docs?
ETA: I am actually using Microsoft 365 for Mac, and I thought that was the problem. Apparently it is the same for Word users in both environments.