The mods announced it today. There’s a giant pinned thread on Beehaw about it.

I tried making posts here on my Beehaw account and I could see them while logged into Beehaw but not when logged into Lemmy.world. Some of my older posts were no longer visible outside of my Beehaw account. Also some of my posts had comments from Beehaw people vanish all at once. My older posts from the Beehaw account are still visible, so I think some posts/comments remain visible if they happened before defederation.

I’m not sure which levers the mods there are pulling because the effects do seem inconsistent, and the mods seem in a bit of a frenzy trying to figure it out themselves.