WetGeek
thanks to recent updates I was able to spend a hassle-free day in XFCE being productive. As far as your pending tracker ticket, I still have no apps going white (light) except xfce print dialogue box---they are all different shades of black despite "appearance settings box".
you mentioned your problem was specifically quogir/dark being ignored in certain apps when you set those certain apps to 'system settings.'
in my multi-black xfce world, I can set firefox and librewriter to system settings dark theme but still they pick their own blacks. We have the same problem, different colors.
the only thing that goes white on me is the xfce print dialogue UI when I want to print something. budgie too.
I'm still learning theming here. I believe the-gtk
theme packages work here best.
XFCE was so buggy I had to turn my back on it for a week but the latest updates have made this really pleasant. Was a nice work day in it overall.