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
The cat becomes the mouse yet again 🥱
not quite , this is way more serious than refusing to give extensions access to websites content. ( for those who don't know that's what manifest-v3 essentially do )
I do wish Firefox would be more customizable about what sites an extension can access though.