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 and let the community decide
- Discuss the issue on chat, with Raiders of the lost downboat being a great choice
And thanks @Esther for making the effort!