Same dam thing happen to me with my Fallout 4 saves. Lost YEARS of save games. I had an external drive save but it was almost a year old.
This &%**$% @^*& *%^&^ "cloud" crap that I always turn off but steam turn it back on without my knowledge or consent. Probably during a client update or the dam fallout "store" trying to load new crap to my PC.
I really hate how the internet has changed my games.
Edit: out of curiosity I looked at my own stuff on remotestorage and there are hundreds of files. So Steam has been doing this without my consent for a long time. However everything is OLD (2021 and older). Anyone know how I can DELETE all that crap off of that location?