I’m not sure if this is new, but when I clicked on the /r/pics protest post link from the frontpage here, I was redirected to this: https://old.reddit.com/premium
I’m not sure if this is well-known or not that they’re pushing it now, but it’s the first time I’ve seen it, especially on old.reddit.
https://web.archive.org/web/20181005224103/https://old.reddit.com/premium/
Looks like Oct 2018 it was started