It seems simple, but I think I’m not competent enough.
I downloaded qt5ct and tried to use it following this instruction but I had no luck, just had to force shutdown the laptop after I created the .profile and tried log-out log-in
Maybe since plasma is a qt5 desktop already maybe I don’t need the qt5ct
Also if it might be important when I do echo $QT_QPA_PLATFORMTHEME like said in your bug report it gives me an empty result