Also you missed that they changed the definition recently, because you don't visit the other site (fair enough):

https://www.reddit.com/r/firefox/comments/1p7k50p/firefox_monthly_active_users_increased_by_about/

So the real usage is actually closer to 150 million, or 70 million less users in 7 years, or roughly 10 million a year

So like I said, nothing to do with AI, it's pretty clear them avoiding AI is doing fuck all, it's not increasing their user share with other users looking to get away from AI and it's not stopping users from leaving.