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.
To give them their due (little as that may be), this only seems to prevent users from logging in to the mobile web interface, not from viewing content as a random user from Google.
Which means users will log out if they want to use reddit that way, and they’ll get even less traffic and data from them then before. The user-generated content they want to sell to AI training models or advertisers will just be less and less and less…
This just further incentivises my intend to delete my accounts and leave Reddit entirely if literally no account is more useable than having one.