[Sebastien Caunes]

You inverted the two color spaces. RGB use 16-235, 601/709 use full values 0-255.

To test it just create a file with a gradient from 0 to 255, compress it with the two options and re-open the two files. You’ll see that both files have gradient going from 0 to 255 because decoder restore levels. But the RGB file has banding, some colors are missing like #04040.

RGB is more destructive than 601/709

as seen on
https://www.reduser.net/forum/archive/index.php/t-13308.html