YouTube is going to use AI to guess your age to determine if the content you're watching is appropriate for you.
"YouTube’s AI will assess a user’s age via multiple behavioral factors, including what kind of videos the user searches for, the categories of videos they watch, and how long the account has been active."

the Guardian
YouTube to gauge US users’ ages with AI after UK and Australia add age checks
Tech company says it will use machine learning to estimate ages in order to show users in US age-appropriate content