I've had that happen before when an rsync command for uploading backups was doing shenanigans. I think, it choked on a very large folder, but I just excluded that folder and then it was fine.

Do you have a second drive? I’ve had that happen when I set one up for extra storage a couple years ago

Check history and see I'd you ran a copy /home to ./ while in home. Or an Rsync command with the trailing vs no trailing slash