Unpopular opinion, but this is objectively better than having to upload your ID to every random website that requires an age check (if that's what the end result is).
Instead of the client sending the user's age to the server, why not make the server send a minimum age to the client? The client is welcome to block content without disclosing personal information to the server. This is as secure as sending an unverified age to the servet.
It started with showing ID at airports and now we have to take off our shoes. Slippery slope is the actual modus operandi of government.
Dystopian nightmares are built from tiny "oh, that's not too bad, just a little step further. Not much different from what we already have"
Making a stupid idea more convenient does not make it less stupid.
You can personally avoid those websites, if you philosophically disagree with those terms. Good luck avoiding the operating system.
In the sense that a website could just ask your OS if you are over a certain age and that age was self declared? That seems fine to me, but why can't the websites just ask me for my self declared age?
That's how things used to be and that makes more sense in my opinion because an OS isn't the thing displaying content. It just run whatever it is told to run.