these apps do not use any official API. if they used it, they would be obliged to comply with the terms of services that most likely force them to show ads or track the users or some other bullshit.
of course these unofficial viewers break from time to time, but in my experience they have been super quick releasing patches fixing it and the user experience is way way better than the official web or app. Fast UI without bloat, no ads, no algorithms, etc.
yeah same for me. Completely moved away from google and only have the account for youtube, and I use that only with either firefox or safari on my mobile devices with an adblocker.
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.
With Firefox on mobile I can use my personal uBlock filter list to deshitify the search results. That alone makes it superior to Revanced for me (still use it from time to time, but every time I search for something I feel the urge to puke).
I recently migrated to NewPipe/SponsorBlock from Libretube and can concur that once you migrate your old subs from the csv google is required to send you, the experience is incredible on either platform.
This plus using invidious with rss feeds and yt-dlp/sponsorblock on desktop, and I've kept up with all my favorite creators without having visited the Youtube site, seen an ad, or heard a sponsor or a call to action in years.
Oh, and on Android, iif you view this article using Mull with NoScript and Ublock on, content is visible wuth no ads.
Add in a bypass paywalls filter list to ublock and yeah...internet is usable again, lol.