EDIT: I see that the “fediverse” link for posts has been removed. I posted this to lemmy.ml from a lemmy.world account and there’s no way for me to get the lemmy.ml link now. And when I crosspost it it shows a lemmy.world link instead of the lemmy.ml one. I think this should be changed [back].

That’s how it’s always worked??? The fediverse button goes to the canonical source, which is the post on the poster’s instance. The button doesn’t show up because you’re already looking at the source.