I just mistakenly made a comment on my post on lemmy.world and while it shows deleted on jerboa (up to date app) I can see it on eternity and attempts at deleting say delete failed (not up to date) but more importantly I can view the comment from my main too.
Is this a federation issue thanks to 0.19, a pre existing federation issue or something else? This could be a serious issue if someone copy/pasted their password or smth by mistake (as I nearly did).
In my experience edits and upvotes federate completely. Deletions apply to your server and the server that hosts the community, and some other servers.
I haven’t figured out what is causing the random behaviour of deletes, but as a workaround, you can edit your comment into an empty post and then delete it to hide the information as best as you can.
That said, consider anything posted on the Fediverse to be there permanently. I don’t think anyone malicious is scraping comments per se, but ActivityPub implementations are so buggy that you simply can’t expect edits or deletes or any other interaction to arrive at all servers that received the original post.