They explicitly don’t:

The law does not require photo ID uploads or facial recognition, with users instead simply self-reporting their age, setting AB 1043 apart from similar laws passed in Texas and Utah that require “commercially reasonable” verification methods, such as government-issued ID checks. Assemblymember Buffy Wicks, who authored the bill, said this “avoids constitutional concerns by focusing strictly on age assurance, not content moderation,” in a press release. The bill passed both chambers unanimously, 76-0 in the Assembly and 38-0 in the Senate.">

I get it, but if bigger projects don’t move to alternatives, those alternatives have a lot less pressure to evolve. If a big project bites the bullet and moves, then there are more technically minded folks with a vested interest in making the platform better.