> "please confirm your age" screen is now mandatory during the iPhone setup in all countries

Not quite.

The request to confirm age is there, but actually completing it isn't mandatory (though granted, it does leave an 'alert' thingy on your phone settings saying you haven't finished setting it up).

It locks down devices like ransomware, permanently restricting functionality of web browsers, messaging apps, and other apps until the user submits to age verification. Its mandatory if you want your device to function normally without restrictions.

There is no "skip" button available.