I'm all for ad blocking and accessable websites, I just don't think the ADA covers ad blocking through the WCAG.

How would you apply those (or others you think are more appropriate to ad blocking) given that the guidelines are for service providers and ad blocking is usually done client-side.

Probably under WCAG Principle 4: "Content must be robust enough that it can be interpreted by a wide variety of user agents, including assistive technologies." If we're treating ad blocking as an assistive technology, purposely attempting to break an assistive technology would run counter to that principle, much in the same way that purposefully breaking a screen reader would (although, it should go with out saying, purposefully breaking screen readability is much worse).

I'm not sure if that's changed since 2019 or not. California has more specific legislation that covers that, though.

I'm wondering if legal action is something that could be done on a state by state basis starting with California (which conveniently is where Google is headquartered) or if the case could be made that Youtube is used to stream live events and those events should count as a physical nexus under the ADA.