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.
I literally just had an instance of opening a nsfw reddit link from a Google search and it informed me that I could only see nsfw posts in the app…
It has been that way for a while. Anything where you have to confirm you’re over 18 will not display unless you’re logged in.