Federation broke after I upgraded to lemmy 0.19.19 (I tend to apply security updates relatively fast). Unfortunately, that broke federation due to some issues in the release. The issue is described here: https://github.com/LemmyNet/lemmy/issues/6581 - they've not released a fixed version yet, but that was easy enough to sort out manually.
There was also an image issue. I don't know what happened there, but imagemagick was consistently failing - once I restarted the containers, that problem seems to have gone away. I don't know if it will return or was something held over from the update - perhaps an unclean restart. I'll keep an eye on it, but let me know if you see it again.