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.
Destroy reddit speedrun any% [WORLD RECORD]
Yeah the desktop site especially is why i wanted to leave reddit for the past few months, im happy they shot themselves in the foot the past week so we could move over to a different platform. I kept having to switch back to old.reddit just to see a NSFW post without an account, they made it so you cant even sort comments anymore without being logged in recently. Just malicious design. The website on mobile has been shit for years now asking you to USE THE MOBILE APP.