You can't cast to Chromecast (non-googleTV if that matters) from Firefox mobile, also pull to refresh doesn't work in browser, and they dont support push notifications for uploads. Revanced works great so I see no reason to switch, and it's based off of the official YouTube APK so you're only logging into Google play services, and you get the same native app experience you're used to with all the addons you'd get from browser extensions built in (adblock, shorts block, sponsorblock, return dislike, background play, etc.)
I don't think there's anything that YT in Firefox mobile can do that revanced can't, but revanced gives you cast support (through the official cast shim that supports CEC for pause, play, stop using the TV remote unlike doing screen mirroring of your phone where you can't use your phone for anything else while mirroring) and other niceties like notifications and one tap to newpipe player / download video file through newpipe. It's only a benefit to use revanced over the mobile web.
That's where all the good pirated content comes from