Yesterday morning I noticed I had a forced windows update, also noticed I had dropped from almost 75+/- GBs of HD space to the low 20s. I assumed it was the update. After spending an entire day backing up and cleaning my system I looked at how the HD space was allocated. Digging in folder what I discovered was that in 3DCoat-2021/UserPrefs/UserScenes I had 45 GBs of old auto saves taking up HD space. Deleting them solved the problem. I don't know If that really a bug but it seems like you could create issues for a lot of users.
I'm currently on version 2021.61, but I'm going update now.