If a company is unethical, they will ignore the Mozilla standard. If a company is ethical, they don't need the Mozilla standard, as they can adopt their own tracking-free methods of serving ads.
I have been told repeatedly by Firefox advertisement advocates that PPA only affects people that don't use ad blockers, so it allegedly only affects people that are already blasted by tracking networks to the fullest extent possible, while people who use ad blockers wouldn't see the supposedly less invasive ads anyway. So it's either 100% tracking to 110% tracking, or 0% tracking to 0% tracking. Seems like a lose-lose scenario for both sides of the equation.
I think that's the point: Google has been shutting down Manifest V2 extensions one step at a time, and it's been experimenting with anti-ad-block tech on YouTube with one user group at a time.