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.
It is off by default. Admins can set the content retention policy on any community.
On piefed.social I’ve set pretty much every meme, shitpost and anime community to expire after one year or less. Check the sidebar of the community to see, it’s beneath the moderator list.