I used to use NewPipe back in the days of yore. Then I got Youtube Premium since it bundled in Youtube Music as well which I used. But the former's app on mobile is a shit show. Even after paying, you are asked to tip random creators, purchase merchandise[ which are shown as actual ads below videos] and join channels to access exclusive videos for more money. Basically pay money once, and then pay more money for more content.
Okay, one could argue atleast the above goes to a channel's creators and helps them. How would one say then that the Youtube app still doesn't have a systemwide option to choose video quality for all videos. New Pipe had that option long ago, but Youtube thinks it's user base are immature who need to be coddled with only two options like "High" and "Data Saver".
Despite having a Premium thing, I finally crossed over to a Newpipe fork Tubular [available on F Droid] today simply because the paying experience on Youtube Mobile is so bad. I can't fathom how bad it would be for free customers using the official app.
I just checked Google support site and apparently the limit is 100,000 songs now, which is quite great. The problem is, they don't tell if and how much, is the music compressed when uploading. Even flac is listed as a supported format but if Google starts storing bit perfect flac without compression, they are gonna give way way more than 15 GB before a power user can hit halfway their song limit.
Functionality is also nonexistent on administrating uploads in YT Music. At least on GPM you could edit basic tags and upload/edit album art. None of that on YTM