found nothing too, but on the othere hand even the archarbor puzzle is disabled, so there might be something, just disabled too

It looks like the whole conundrum of the issue is that Reddit own mobile website or mobile apps are not correctly showing the message on the closed sub, but only that it is now a private sub, see https://dormi.zone/comment/90345

So I see the issue is what the mobile website/app shows you

This is what is visible at https://old.reddit.com/r/Warframe/ on desktop browsers:

And this is what is visible at https://new.reddit.com/r/Warframe/ on desktop browsers:

Then you should complain to Reddit for hiding you useful information to you, simply because doing that it is not useful for them, and not complain here to dormi.zone

Also wait the 30th of June when "where most users are", that is on mobiles apps and not on the mobile website because that one sucks badly, won't be able to see reddit at all, not only one sub