Safari 15 keeps logging me out of several sites every week or so

I've increased "remove history items" to 1 month - no luck

I've disabled all extensions - no luck

Still there are some sites which keep me logged in, but google.com, youtube.com, facebook.com, ebay.com - they are all throwing me out every week.

Other browsers doesn't do that.

Safari 14 didn't do that.

Am I alone with this porblem?