This is a massive mistake. Eric Goldman from the very excellent Technology & Marketing Law Blog has consistently produced insightful commentary on this over the past several months. From today:

When a proposed new law is sold as “protecting kids online,” regulators and commenters often accept the sponsors’ claims uncritically (because…kids). This is unfortunate because those bills can harbor ill-advised policy ideas. The California Age-Appropriate Design Code (AADC / AB2273, just signed by Gov. Newsom) is an example of such a bill. Despite its purported goal of helping children, the AADC delivers a “hidden” payload of several radical policy ideas that sailed through the legislature without proper scrutiny. Given the bill’s highly experimental nature, there’s a high chance it won’t work the way its supporters think–with potentially significant detrimental consequences for all of us, including the California children that the bill purports to protect.

I highly recommend reading Eric's full take on this. He breaks down five separate aspects of this that don't really add up at all: not only does it shift the Overton window towards surveillance-by-default (face scans on any website that a minor might try to visit, for example), but it also disempowers parents to make decisions about how to raise their child, which is exactly the wrong approach, all while adding a lot more friction to navigating an already-immensely-confusing internet.

Gavin Newsom signs California social media overhaul for minors