Interesting--I'm still using old.reddit.com with no problem, without an account. Maybe the change is not broadly rolled out?

They’ve been rolling it out gradually. There was a thread on HN about it a couple of weeks ago, it just started affecting my IPs a few days ago.

It’s managed to do what years of self-imposed content blockers etc. on my own side have failed to do - finally broke my Reddit addiction!

Could be regional - however it's odd that it pops up on old.reddit.com but not reddit.com.