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/web/20230611224026/https://old.reddit.com/r/help/comments/135tly1/helpdid_reddit_just_destroy_mobile_browser_access/jim40zg/

  • Earlier today, I was reviewing some Lemmy information in Google, and one of the links was to Reddit. I didn’t think anything of it, but I clicked and saw the message that’s given to mobile users saying you have to view NSFW content in the Reddit app. Fine, I’ve got the garbage app installed already for situations just like this. I click the link, and it throws an error stating my third party app (Boost, in this case) must be uninstalled in order to open links in Reddit.

    No it doesn’t, Reddit. And why do you care what’s installed on my phone?