(it doesn’t tie your identity to the content you’re viewing, only the use of your credits)

The website can't know this, but the government can easily (and I bet will) link an identity to a token, and know where and when it is used. It can also request metadata on usage of a token, which websites will no doubt want to store.

That the government can track this sort of thing is bad enough, but I'm especially concerned that it or both parties will leak/share/sell their databases, allowing anyone to do the same.

I think this is bad because it doesn't solve any problems (efficacy of age verification systems is questionable at best) and introduces new problems (token system violates privacy). Censorship under governments creates black markets and reduces privacy at taxpayer expense. If they are concerned about child safety maybe they should start with what studies show are the most effective ways to accomplish that goal as opposed to ineffective, expensive wastes of time.