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.
https://web.archive.org/save/https%3A%2F%2Fold.reddit.com%2Fr%2Fhelp%2Fcomments%2F135tly1%2Fhelpdid_reddit_just_destroy_mobile_browser_access%2Fjim40zg%2F
They sure are racing to the bottom as quick as they can huh?
This is just the natural consequence of IPO's and generally what happens when greed replaces stewardship and community. Profit-seeking was always at odds with user-driven content, it was managable up untill big stupid money managed by disinterested parties got involved, and now we're just in the late stages of Enshitification.