Something big is happening, as Reddit seems to have purged literally every NSFW sub they know. Reason is always "unmoderated" despite some of the banned subreddits being fully moderated.
Edit: seems to have been a bug in automation (thanks @[email protected]):
https://old.reddit.com/r/ModSupport/comments/1ii67mt/_/mb3fewv
It's still a good reminder on how quickly a community (or communities) thousands of people enjoy and in some cases rely upon can disappear.
In the top right of your internet browser, there should be a menu button. If you hit that, there should be a "Desktop Site" button. If you check that, the app prompt goes away. It's annoying that it's required, but at least you won't be locked out