Well I duplicated the docker container but added a volume for a temp folder. It looked like some BTRFS versioning was saving every temp file all the time. Figured that is unnecessary and moving it to a more accessible location would save me time if I had to remove it again.
Fired up the new container and working fine. Erased the old container (took quite some time) and got my space back.
If this isn’t a fluke, it may be a good idea to add a little line to the docker repo info.