As quoted from the linked post.
It looks like you’re part of one of our experiments. The logged-in mobile web experience is currently unavailable for a portion of users. To access the site you can log on via desktop, the mobile apps, or wait for the experiment to conclude.
This is separate from the API issue. This will actually BLOCK you from even viewing reddit on your phone without using the official app.
Archive.org link in case the post is removed.
Yeah, maybe it’s an exit scam. I bet some executive said, “I’ll give the higher up execs what they think they want (ADS) which is the opposite of what the users want, but we’ll all get bonuses just before the site dies.”