FWIW: that post is not for 2 communities - it’s for one community (/c/test at sh.itjust.works) and one user (/u/test at lemmy.ml) - I’m guessing that it’s autocompleted to a thing that was different from your intentions.
(edit: the webfinger response from lemmy.ml for ‘test’ returns both a Person and a Group, which Lemmy can deal with, but Mastodon probably can’t, so it just grabbed the first one it saw)
Federation delay from lemmy.ml to lemmy.world:
https://grafana.lem.rocks/d/cdfzs0dwal3pca/federation-health-time-behind?orgId=1&var-instance=lemmy.ml&var-remote_software=lemmy&from=now-30d&to=now&var-remote_instance=lemmy.world&timezone=browser
(It’s been a pattern of spiking up to almost 2 days before recovering).
It’s a LW problem (that they are aware of), and it’s unrelated to whether a comment has images or not.