Have you even bothered to do any research at all into what pseudosignatures are and how they can be used? Or are you just trolling?
Valve could simply set up an instance of an eID server software and get a digital certificate for it authorized by our respective national PKI chain. Functionally the same to how TLS certificate chains work. There is zero technical need for any information to flow between Valve and any other party - the state or otherwise - about who is being age verified. And Valve would not be able to get any information about you other than what I've already explained.
Seriously, the brainrot on here seems to be as bad as on Reddit. And btw: This has been state-of-the-art for more than ten years.