The YouTube mobile website is intentionally crippled. For example, the video refuses to play in a video popout, even though the same browser feature works for me on other mobile websites and on desktop YouTube. Personally I just avoid browsing it on mobile as a result, but I could see someone being convinced to install the app.
On iOS, installing vinegar sorts this. You get video pop outs and no ads to boot. It’s much better that the app and seems to give longer battery life (hardware acceleration?)
It breaks integration with the YouTube app, and it's a bit of a maintenance keeping up with the latest version, whether to use youtube-dl or yt-dlp or another fork, etc.
I paid $1.99 for Vinegar and on my iPad (and Mac) I get ad blocking, videos playing in the background, etc. It can be a little clunky because autoplay of the next video doesn't seem to work and there are times I'd like to use a music playlist. It's probably my fault but a quick glance at settings didn't resolve it.
I use the web one exclusively. Other than the video pop out feature missing and once in a while scrolling bugs on shorts, it actually works perfectly fine.
I refuse to use the YouTube app because they disabled playing in the background or with the screen locked . They Want your eyeballs on the screen for the ads. It so blatant.