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.
Makes sense, I’m to lazy for pi-hole or what so ever to be ad free on mobile. But I also hate apps for what could be a website, so I used old reddit on mobile.
I use Blokada 5 to block ads on my phone and it works pretty well. That version is free, but Blokada 6 is their subscription based blocker which is why I specify the number. I have no experience with 6.
I usually hate apps for websites, but old Reddit is too hard to read on my phone so I used third party apps.