YouTube's age-verification move is another step in the growing age-verification push that is being hastened by the US and other governments trying to prevent children from accessing content deemed harmful, unhealthy and not appropriate for their age. If its age-estimation system decides someone is under 18, YouTube will then:

YouTube is launching a new test in the U.S. they’re using AI to estimate a user’s age—no longer just relying on birthdays signed in the profile.