Reddit is removing the Direct Message feature, and all active conversations will be archived so you won’t be able to continue ongoing conversations. Reddit also deleted all bad reviews for their app awhile ago. Its rating went from 3.4 to 4.5 stars overnight.
For me, it’s that the app I use does not have the chat feature. I’m 99% certain this is just an attempt to push out the revanced users
Chat is only available in the official client, the implementation is closed source. So yeah most likely that.