Inconsistent windows decorations

Hi there,
I have a little issue of windows decoration with some applications (Firefox, Opera, Thunderbird). This issue was present with plasma 5.27 and persists with 6.0.4. While MacVentura-Dark is used by the whole applications and windows, the above-mentioned applications have different windows decorations like “Plastik”. After searching the internet, I wonder if it could be a GTK problem but don’t know how to fix it.

for a Firefox solution.

Thunderbird, Brave and Telegram have similar settings for example.