First off, this page references quite a few bills passed, some of which I like and some of which make me concerned, but let’s focus on AB-1043. You can find the text of the actual bill here.

Here’s the more relevant excerpt:

1798.501.
 (a) An operating system provider shall do all of the following:
(1) Provide an accessible interface at account setup that requires an account holder to indicate the birth date, age, or both, of the user of that device for the purpose of providing a signal regarding the user’s age bracket to applications available in a covered application store.
(2) Provide a developer who has requested a signal with respect to a particular user with a digital signal via a reasonably consistent real-time application programming interface that identifies, at a minimum, which of the following categories pertains to the user:
(A) Under 13 years of age.
(B) At least 13 years of age and under 16 years of age.
© At least 16 years of age and under 18 years of age.
(D) At least 18 years of age.
(3) Send only the minimum amount of information necessary to comply with this title and shall not share the digital signal information with a third party for a purpose not required by this title.

Basically OSes will have to have a prompt during setup that asks for age/birthdate to determine the legal age category they user fits in.

Then the OS has to provide some sort of API that provides that category to apps/websites that request it so they can gate content/features appropriately.

IMO this doesn’t seem that bad. It’s basically taking the “I solemnly swear I’m over 18” checkbox away from websites and just requiring it once OS wide (or at least per user account).

I particularly like the specification of #3 requiring only the minimum info required to comply be sent and nothing more.

This actually seems like an attempt to curb all the ID collecting privacy nightmares that are happening lately with poorer implementations.