I'm not sure what you are talking about. Mozilla had some distractions, yes, but Firefox is a fine browser, and it supports full-featured uBlock Origin including on Android.
Transparently - I've been relatively deep in the extensions space across every major browser (Chrome/Safari/Edge/Firefox).
Based on my interactions with their browser team during this process - I'm no longer a supporter of Firefox. I want to credit the engineers and support personnel I interacted with there for doing their best despite their company policies, but their policies became insane (And since you mentioned ublock - here's Gorhill, the author, expressing basically the same opinion here: https://github.com/uBlockOrigin/uBOL-home/issues/197#issueco...)
I won't recommend using it: I don't think it's trying to serve its users, I don't think it's trying to serve their developers. I think it's coasting on historical good will, and it's essentially been on life-support as a cash grab from Google since they laid off their engine team in 2020.
Combined with increasingly non-sensical product releases (ex - this one) and "security marketing" that doesn't match reality... I find the whole thing fairly distasteful at this point.
I'm already getting tons of captchas from the likes of cloudflare in Firefox on Linux. Because somehow I'm suspicious. That's not the sign of a browser doing well.