Last I checked, Firefox had also been switching to Manifest v3 because they're also combating the tide of add-ons that pretend to do something useful, but actually steal your information. They asked uBlock at least a few times how they could build Manifest v3 in a way that'd be compatible. Instead of the browser asking about each URL, thereby giving the add-on access to personal information, uBlock could tell the browser what to block. uBlock's answer was always, "No. That's not good enough. Give the add-on access to URLs." It seemed to me like every time uBlock was approached, they turned to news sites to complain and IIR, the feature that would have given uBlock some functionality was removed from v3 because if nobody's going to use it, why build it?

I wonder, now that uBlock has conflated the discussion of, "How much should extensions be able to see and modify URLs you're visiting?", with, "v3 is a war on ad blockers!", how quickly Firefox will move forward with v3, if at all.