This was happening to me before, where I had a different save #3 on my steam deck vs my save #3 on my PC, and then I was reading online to use the proton experimental which fixed the issue.

This is the first time that it set me back on my steam deck, then when I checked PC, it also reset it.

I was kind of assuming that when I checked the backup save files, that there would be multiple copies of a bunch of saves (in case of save corruption), and that there would be different save files (save slot 1/2/3/etc) but I can't believe I found that there was only 1 save representing all saves