Mozilla should call for Google's removal from the W3C over this implementation of Web Environment Integrity. "But Chrome has 65% market share, what good is the W3C without them?” If Google can take unilateral action to fundamentally change the basic principles of the web, then the W3C is
already useless. This will give Google a clear choice: if they want to maintain the idea that the W3C matters, they should withdraw this implementation.
It is unbelievable that over the course of 3 days, the potential future of the web has been put in such dire straits. There's already an existing, far less troubling (while still bad), proposal in the form of Private Access Tokens going through a standards committee that Google chose to ignore. They presented this proposal in the shadiest way possible through a personal GitHub account. They immediately shut down outside contribution and comments. And despite the blowback they are already shoving a full implementation into Chromium.
What we need is real action, and this is the role Mozilla has always presented itself as serving. A "true" disinterested defender of the ideals of the web. Now is the time to prove it. Simply opposing this proposal isn't enough. This is about as clear and basic an attack on what fundamentally differentiates the web from every walled garden as possible. If someone drafted a proposal to the W3C that stated that only existing browsers should be allowed to render web pages, the correct response would not be to "take the stance that you oppose that proposal," it would be to seriously question whether the submitting party should even participate in the group. Make no mistake, that is what is happening now.