I switched from Chrome to Firefox in 2019 because that’s when Google adopted Manifest V3 and I never looked back. There were already articles then describing how it’d break ad blockers, and Firefox had at the time just recently released their “Quantum” overhaul which drastically improved responsiveness.
I’m a bit surprised it took five years for Google to drop support for Manifest V2, but the threat has long been there.
I remember the Quantum release. They remade how the browser handled tabs, and with the new release you could handle (almost) unlimited number of tabs. I tried this buy opening as many tabs as I could, it worked flawlessly. I can’t even remember how it was before that, except that it was RAM intensive.