After last UPdate (20230710), my Pamac shows up with black background, although all my settings are “light”. All other KDE-applications follow the setting and are “light.” It’s only a problem in Pamac, not a big deal.
If seen postings here and there having recommendations from @Mirdarthos and checked
Since @philm admitted that pamac gtk4 will not follow Plasma gtk theming because libadwaita, it’s all explained and there is no need to experiment and look further.
I just switch to pamac-gtk3 and forget it.
Thanks all for the comments and helping me to understand and solve this problem.
This is how pamac-gtk3 looks like and how it supposed to look like all along :