If I delete a post from on another server, it only disappears from my instance?
I posted something on lemmy.ml (mine is lemmy.world) and deleted it right away. I thought it was gone, but a few days later I searched my profile on Mastodon and saw the post there, with many comments. Then I checked the community from another profile and my post was threre.
Was this a bug or we can only delete posts from our account server?
It sometimes takes a while or a second try due to how things work between instances. You told your instance to tell the other instance to delete it, but sometimes the other instance doesn't get your request or there is a queue of other requests slowing yours down.
I noticed this with posting, too. This comment itself might not show up for a few minutes because I'm on a different instance than the post is coming from.
If servers are overloaded, federation will never happen, whether posting, editing, or deleting. It's just not that reliable all the time.
It's probably because the federation takes some time. Check back later.