Sorry for the content links here to explain a problem (I am happy to delete this if requested).
If you open a private browser and visit https://www.youtube.com/watch?v=zzk2Gmi8A1E you will see it requires an account to verify age.
If you then visit https://www.youtube.com/watch?v=i0jstgVnhxo you will notice there is no verification of age.
What is the point of mandating age verification, if platforms cannot categorise the age appropriateness of their content in the first place?