OneDrive is the devil. It symlinks the file structure on Windows and then moves all your photos and such into their chosen directory. If you uninstall it, it makes a half-hearted attempt to move them back, maybe, but will just do a random subset and give up.
After removal, you have to edit registry keys (obscure ones) to break Windows’ connection to onedrive\pictures and such, or you end up with two pictures folders in your home dir.
So much more fail I can’t even remember right now.