lemmy.ml and dbzer0 are silenced on piefed.social, which makes their communities hard to find.

But if you go to their url directly you can join them like normal:

https://piefed.social/c/asklemmy@lemmy.ml

https://piefed.social/c/piracy@lemmy.dbzer0.com

There is no hardcoded instance block list. There are some instances that are defederated from initially when an instance is first created but the instance admin is told about this when it happens and they can change it by clicking around in the admin area. More info at https://join.piefed.social/2026/08/13/what-piefed-blocks-out-of-the-box-and-how-to-unblock-it/