By the sound of it, the disagreement is mostly in how direct an impact AB1043 will have on government plans for data collection and authoritarianism.

That's not really the original disagreement i was referencing, nor is it a position i've taken, we agree that the local only bill isn't the big bad.

You twice referenced the slippery slope fallacy when replying to comments clearly describing future actions, i was pointing out that it doesn't meet that criteria because there is a reasonable assumption that the described escalation will occur.

Your original responses to which i was referring:

This is a slippery slope falicy. Just because the option is provided to self-identify age, doesn’t mean that it will be replaced with more complex and direct data collection (which I am against, if it wasn’t clear) later

You’re again relying on slipery slope falacy to say that because I’m okay with this one specific form of age gating, I’m okay with every other one, which I have repeatedly made clear is not true.

The first one is the main issue i was pointing out, the second one isn't how the fallacy is applied at all.

As no one is taking the position that AB1043 is the actual danger most of what you are arguing doesn't really apply.

Similarly with the Overton window, where it has been standard practice for over a decade to have a “are you at least 18?” popup, and for every single service to ask you your age, if not more. We absolutely need more data protections for systems such as this (ideally an outright ban on saving this information) but this doesn’t seem to make it worse.

Emphasis mine.

Hard disagree, moving the responsibility of this from individual websites to the OS is a big jump in scope.

The same kind of jump as making it the ISP's responsibility if they serve illegal content from individual websites ( as has been suggested ).

Aside from that it centralises the surface area for future changes and enforcement.

Basically, from my understanding, this isn’t a step towards data collection or authoritarianism, and provides no significant benifit to either of those causes - its effectively a technical standard.

This is the disagreement, i (and obviously many others) are pointing at the long and comprehensive list of similar initiatives, both recent and historic, that were stepping stones to further encroachment and saying "oh look another small step in the continued and provable encroachment upon privacy" and you seem to be advocating for the benefit of the doubt.

Like, if this age-verification flag was proposed by the Linux Foundation, and agreed to by others, would the backlash be this big?

If the linux foundation had the same history of shenanigans, then yes.

Similarly, I don’t see any contradition between wanting a ban on storage/sharing of user data, and the implementation of a flag like this - even if we are able to ban all storage of user data, this law would be unaffected. That’s what I’m trying to figure out - how do people think that this leads towards those end goals? How would blocking it improve anything?

Ignore the technical implementation of this one step, nobody is saying this is the endgame big bad.

Think of it as a prevention measure, a single ant in the kitchen isn't a problem in and of itself, but it's almost certainly an indication of a larger potential future problem.

You are arguing it's not a problem because the ant only has 5 legs, everyone else is saying the leg count doesn't matter it's still an ant.

Is it just a difference in opinion about the signicance of the Overton window?

See above

Is there a technical aspect I’m missing?

Not necessarily , it's just that you are arguing a single technical issue in a conversation about perceived intentionality.

Is there some legal advantage this provides to survailance that I’ve missed?

See above

Right now, it seems like everyone is arguing against a strawman, implying that I support the idea of government/corporate surveillance and censorship, that I don’t expect that they’ll continue to be evil, or they’re simply saying its bad because its cosmetically similar to laws that do impede on freedoms. Given how unanimous the backlash is, I must be missing something?

That you are using a point nobody disagrees with to imply correctness in a context where said point doesn't really apply makes it seem like you are coming at this in bad faith.

When bad faith is assumed, people look for underlying reasons.