You’ll see two like buttons and you won’t be able to unlike the post
I’m guessing the logic that doesn’t allow you to like your own posts kicks in when you transfer ownership and that is why you can’t unlike the post as the new owner.
What I figured out is that the ownership transfer works just fine in removing likes if the ‘unlike’ timeout window hasn’t been reached yet, but if that has been reached, like on an old post, that is why the likes didn’t get removed because it fails to pass the guardian check of being able to unlike your own posts.