Lords of the Fallen: Save File Location

The save file location for Windows 10/11 is:
C:\Users\”YOURPCNAME”\AppData\Local\LOTF2\Saved\SaveGames

Thanks to: @JesusLuvsU
And if you are on Steam Deck/Linux: (note turn on hidden files and folders)
/home/deck/.steam/steam/steamapps/compatdata/game id/pfx/drive_c/useres/steamuser/AppData/Local/LOTF2/Saved/SavedGames

Download steam cloud save from here:
https://store.steampowered.com/account/remotestorage

Choose one on a day before the corruption occur. Place it in:
C:\Users\”yourpcname”\AppData\Local\LOTF2\Saved\SaveGames

And lastly you can try:
On the local folder also, delete the current save, and remove the Backup part text of the back up save. That could potentially also help, if the backup save file is not corrupted it self.

I also suggest to do manual backups of the SaveGames folder. Just copy and paste the same folder to another drive, or zip the folder after each session.

Make sure to do this regularly to not lose huge amount of progress, in some cases with hundred of hours play time.