looks like rendering adblockers extensions obsolete with manifest-v3 was not enough so now they try to implement DRM into the browser giving the ability to any website to refuse traffic to you if you don't run a complaint browser ( cough...firefox )
here is an article in hacker news since i'm sure they can explain this to you better than i.
and also some github docs
I work at a vpn/adblocker company and we just finished releasing an updated mv3 extension that does block ads effectively (among other things) but the feature set is limited vs mv2 because of the changes. Furthermore, google has actually pushed back their mandated release schedule for mv3 compliance because something less than 30% of the extensions on their store are anywhere close to ready for it (which if they pushed ahead with mv3 they would effectively break 70% of what's on there overnight).
The DRM shit is just next-level bad though. Enshitification 101.
The thing is mv3 is not needed nor wanted by anyone, they are actively shoving an unnecessary product down our throats to show us more ads.
I will keep on using Firefox and Librewolf until the web goes back to webpages that load in text only browsers in less than 2 secs