A lot of issues require holding two ideas in your head at once. Age verification chips away at privacy and internet freedom. It likely also reduces harm to some/many/whatever children, even if it’s imperfect and won’t stop everyone. The interesting question is where the right trade off sits. People often end up arguing only one side.
Massively downplaying it to say "chips away" this takes a sledgehammer to the core of internet privacy. In all cases in the world where this has been done before like China or Russia, freedom is also lost shortly after. Of course people only argue one side, the stakes are losing internet privacy and freedom in the entire world if the west also succumbs to these authoritarian policies. It isn't the government's job to prevent your child from getting access to a phone/ipad, that's your job as a parent.