According to this blog announcement, [1] Manifest 3 was announced on Nov 9th 2020 which had ~223M Firefox users and the last avaiable data says that on Nov 5th there is a ~187M users. This about ~36M not 60M.

[1] https://developer.chrome.com/docs/extensions/mv3/intro/

That's alarming on its own, but I don't think the point of announcement of Mv3 is all that relevant, 99.9% of users aren't going to change their browser until they absolutely have to because they don't know what "Manifest v3" is, much less what it means for them.

Because the MPL/GPL is super restrictive if you’re trying to build any kind of sustainable business directly from Firefox code. Nothing big tech scale, but even just attempting to put food on the table with it risks lawsuits.

Extra credit: compare and contrast with the graph of Baker’s compensation as CEO