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
That's the point, DRM would force everyone to use a "compliant" browser (Chrome, or extension-free Firefox etc), and the other browsers might not be able to show content; they may also lock the content from copying and editing without special tools, just like website video DRM works now
But we already see "sorry you're running adblocker so no content for you" websites, so I'm not sure if that's gonna change much
Firefox works around video drm by running it in an isolated container though.