r/UnresolvedMysteries. I really liked this subreddit. Now I took a look at the thread about API changes which is stickied there and it just seems a lot of people are asking "can someone explain to me what's going on/who cares about 3rd party apps" (and my favorite one - "it's all power-hungry mods' fault"), so it doesn't seem like the community will migrate from reddit.
I miss reading all the write-ups, not only about true crime but also other mysteries.
Thank you, I subscribed! Hopefully it will take off :)
Btw, I got a notification about your reply, and I can see it on your profile, but I do not see it when viewing the thread. Not sure why. Never mind, all is working now.