try to reinstall containerd.io
No change. I also tried a reinstall of docker using dietpi-software and no fix.
I tried to restore a backup from a week ago, but it also had docker+portainer on it (it also didn’t work). At the time of the backup I wasn’t actively using docker, so I hadn’t encountered this issue.
I may try a fresh Dietpi install if I have time on the weekend.
Thanks for your help @Joulinar . I will update here if I discover anything.