Age check is very harming for your privacy. The whole EU want to go into this direction and it worries me a lot.
Just not pornhub but also social media sites etc. The reason why I don't like it at all is that you once again need to share data with parties you don't want to give them data. Especially not your passport.
It's a matter of time before data will be leaked online after a random data breach.
Edit: I also want to add, it's also about full control. They can reject you from websites. And websites can be rejected from this system.