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. The are actually going to BLOCK you from even viewing reddit on your phone without using the official app.
Archive.org link in case the post is removed.
Reddit has amazing SEO, and it looks like Spez is now hell bent on destroying that as well.
What a fucking incompetent moron. Google hates when people put roadblocks over mobile web experiences. Over the past 5-ish years they’ve down ranking sites that obstruct m.web.