Aside from how CinGG works, from what I understand YT recompresses the
original video even if it is set similarly to the way they compress.
In short, YT's compression goes over whatever settings we make,
whatever programs we use (from
https://support.google.com/youtube/answer/4603579?hl=en: "Note that
YouTube always re-encodes videos to optimize their playback quality").
So compression on compression leads to banding.
Ideally, you should start with a poorly or uncompressed original so
that YT compression leads to better results (less banding). The
downside is that a poorly compressed file (Prores, DNx, ...) is about
10 times larger than an h264...