Files moved to .stversions after accidental USB drive disconnect

Hello there. I have a slight problem I would like some help with.

I have a home server (windows) with USB disks attached. On one of these disks resides my music collection which is also part of a Syncthing repo with staggered file versioning. While cleaning I accidentally pulled the USB cord halfway out of the socket and did not realize until 10 minutes later. When I started up the music player on my desktop (windows) it couldn’t find anything, looking up the music folder everything ended up in .stversions. Syncthing apparently thought the files were just gone. Plugging the USB drive on the server back in resulted in those changes being synced back to the server, too.

I now have tens of thousands of files with altered files names which is infeasible to correct manually. So far I have tried to learn regex to be able to rename everything back with Bulk Rename Utility, but no luck.

Search the forums, there are already a few oneliners which help with that. I assume the flash drive is a subfolder in a synced directory?