I disabled docker again and ran mover (logging was already on). I think I have found the problem:
May 9 07:01:56 PlexNAS move: file: /mnt/disk1/system/libvirt/libvirt.img
May 9 07:01:56 PlexNAS move: move_object: /mnt/disk1/system/libvirt/libvirt.img File exists
May 9 07:01:56 PlexNAS move: file: /mnt/disk3/system/docker/docker.img
May 9 07:01:56 PlexNAS move: move_object: /mnt/disk3/system/docker/docker.img File exists
May 9 07:01:56 PlexNAS move: mover: finished
The docker.img on disk 3 is dated 2023-10-17, the one on cache is dated today. I *assume* I can just delete the one on disk3, but I wanted to ask someone that knows what they are doing before I do anything silly. The libvirt.img is the same situation, the one on disk one is dated 2023-11-17 (the day I was clearly hacking at things instead of asking first and messed something up). The one in cache has yesterday's day, which makes sense, I never turned the VMs back on since I haven't used a VM so far.
Is it safe to manually delete the two old copies that are still on the array?