Qt theme looks worse than GTK under KDE Plasma

Description of the issue:
Brave browser under KDE Plasma displays the built-in window control buttons at the top right corner when the user chooses to “Use Qt” Theme, although it displays the correct window control buttons from the active system-wide theme when the user chooses to “Use GTK” Theme (in both cases “system title bar and borders” are not used).
I would expect choosing to “Use Qt” Theme would make the appearance of Brave better aligned with the system than the GTK option, not vice versa.

How can this issue be reproduced?

  1. Install Brave under KDE Plasma (preferably version 5.27.10, on Debian Trixie/testing)
  2. Go to settings > Appearance, choosing the “Theme” to “Use Qt”, and not to “Use system title bar and borders”

Expected result:
Window control buttons on he top right corner should be in line with the system-wide window decorations, e.g. Breeze buttons.

Brave Version( check About Brave):
Brave: 1.64.113 Chromium: 123.0.6312.86 (but this has been going on since I’ve begun using Brave probably a couple of years ago)