This is the reason:
Looks like the PieFed’s old post deletion does not take into account whether a poster is local to a deleting instance or external to it.
At least one banger of mine on this comm is already affected.
Memes on piefed.zip should be safe.
My piefed.social account was an OP of several posts on that community. piefed.social deletes old posts from the comm after 365 days, and my posts made from piefed.social were purged too.
Text and link content, and the discussion technically remain, but the image is broken for anyone in the federation (as Lemmy does not cache external images).
The “delete old posts from an external comm” feature of PieFed is ATM done wrong. It’s wrong to delete a local post only because it was posted to an external comm, whose old posts get purged.