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
Mozilla already stated that they wouldn't go away even if Google stops paying them for having Google as default search engine.
And I'll admit that does provide some level of reassurance. I do worry about Google pulling strings though. I suspect they keep funding Firefox not to promote their search engine as default, but rather to ensure they're not called out as being a blatant monopoly in the Web Browser ecosystem.