https://lemmy.world/c/news@beehaw.org is up to date, my dude.

Lemmy.world users can upvote and reply to /c/news@beehaw.org and this will be broadcast to other instances (like I can see those upvotes and replies on lemmy.ml) but beehaw.org users won't see them.

Defederation blocks specific fediverse content from appearing in the server doing the blocking only. It's NOT a censorship or privacy tool. It doesn't stop blocked servers from pulling content (a pointless endeavour anyway since all information is public by default and could in theory be pulled from unblocked third parties). Defederation is specifically a tool to control what instances are available to view from the instance doing the defederation, and perhaps most importantly, to keep content legal for one server to host entirely off a server where that content is not permitted (like Nazi stuff in Germany, or porn in many other places)