Some great detective work! I have closed 2-4 as duplicates of your number 1 question as there is a basic premise of: Slack currently is broken, revert to an older version. Doubtless there will be more new questions along the same line...

There are some choices when you have found such a run of dupes, and I make the following list *in no particular order*:

 - Make a post on Meta (as you have done)
 - Leave a polite note under the question querying a Duplicate (as you have done)
 - [Flag for closing as a Duplicate][1] and let the community decide (3,000 Rep)
 - Discuss the issue on chat, with [Raiders of the lost downboat][2] being a great choice

And thanks @Esther for making the effort!


  [1]: https://askubuntu.com/help/privileges/close-questions
  [2]: https://chat.stackexchange.com/rooms/3877/raiders-of-the-lost-downboat