They can normally if their instance is not defederatd.

But if beehaw defederate some instance, only the one from their own instance can see and interact with their post.

So for example, I have an account in lemmy.world and posting it to beehaw tech community. Other user from lemmy.world can see my post and reply normally. But other user from other instances (including beehaw itself) can’t even see the post.

Basically like shadowban in reddit but for all users in an instance