An unusual one, I’m not multiple days late for something!
I’m not entirely sure it needed a complete API redesign, it would’ve been enough to add the missing endpoints. They current API doesn’t let you retrieve the replies to a Tweet, so showing a conversation is practically impossible. (I’m aware that there are workarounds, e.g. by using the search and then some filtering, but that’s limited by the API too), doesn’t let you access polls (not even that a tweet does have a poll), so it seriously limits third party apps. As a happy user of Tweetbot I very much welcome this change. I’ll just hope that they will stop bullshitting developers, Twitter burned some serious bridges there.