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, I have put in a lot of time in some of the communities over there and would be sad to leave, but I refuse to continue to drive conversation and generate the content for a site that has such low regard for their users.
We’ll see how it develops, but I am sad to say that it looks like the writing is on the wall.