“When it detects a user may be under 18, Google will notify them that it has changed some of their settings and will offer information about how users can verify their age with a selfie, credit card, or government ID.”
Selfies are useless as proof for young adults and people with a young face. No algorithm can tell a 17.11 yo from a 18 yo so it will flag every single one of them.
This is a way to normalize handing over your details for the next generations. Nothing more.
The good news isn that once teens figure out that other browsers and search engines don't stop them from finding porn they might stick with them.