My partner was on Windows 10 and was running into some issues with OneDrive. Apparently it just moved the entire user directory (or something like that) to OneDrive and most of his files were not local. We tried to disable OneDrive and his Desktop just disappeared.
We finally just got rid of it, but it was a pain and I don't think he ever turned it on. At least not purposefully.
Also please don't say to just use Proton and SteamOS for gaming. I have had enough issues with games not working under proton (Particularly if not from Steam) or updates breaking games on my Steam Deck that I also use Windows LTS on my Steam Deck most of the time now.
Edit: I remember what the problem was. he ran out of space. So the service that he didn't sign up for (at least purposefully) that synced his entire home directory stopped syncing because he ran out of space on it, and his files are basically being held hostage by OneDrive.