I fully understand this to be a controversial take, but I think it is important to acknowledge that not all advertisement is the same. While I dislike all forms of advertisement, I only take issue with non ethical ones, which are based on surveillance. I don't have any ethical concern with contextual advertisement which is how some search engines provide advertisement, such as giving advertisement for food when searching for food.
But it is also critically important that extensions remain a part of the browser, to give a certain level of control to the person navigating the web instead of just allowing any website to freely track our activities.
I don't know what the path forward is for Mozilla. Google is unlikely to be able to fund Mozilla the way it has until now as a recent ruling which has deemed google as a monopolistic actor clawing at its default status everywhere it can. This was a major founding source for Mozilla. They need to figure out financing and while it is easy to criticize, we must also recognize the challenge it is to give sustainable and important funding sources to Mozilla. I really wish I had an answer... Can it somehow depend exclusively on its users for donations? Should It sell support services? Should it branch into more lucrative areas? If yes, which ones? It may need to be a combination thereof but for now, I'm personally blinded. We need to get together on this, because if we can't help Mozilla, can we help anyone who might fall into this situation?