Out of the box it can play audio in the background, and now that extensions are available you can block ads as well. You don’t really need constantly updating 3rd party clients or questionable firewalls anymore if you just want usable youtube on a phone.
Youtube revanced lets you select a prefered quality setting for wifi and a separate one for mobile data. It will force the quality into that setting or the nearest one to it if it’s not available in as high a quality.
This alongside adblock, sponsor block, and lots of customizable UI improvements.