I use a bright theme in KDE6/Wayland (global=Breeze, color&plasma style=Breeze light(?) (“hell” in german)
But since some days parted shows a dark theme, where the symbols are nearly hidden. I cannot remember when it started with bright theme, perhaps before KDE6.
Problem solved!
The application style was set to Breeze, so at first I thought that was OK. But after switching to Default (Emacs was OK, too), parted was set to a light theme.
Thanks, marked this thread as solved.