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
Louis Rossman made a video about this and especially where he quotes users from HackerNews hammers the point home for me. Firefox will be forced to adopt this "feature" if it ever becomes reality, as Chrome has overwhelming market share and the average user only cares that the site loads.
Firefox won't even implement something as mundane as WebSerial because Mozilla has deemed it "harmful", I really can't see them going along with this.