How to theme QT Flatpak apps ?

I am running Sway on Debian 12 and I just can’t succeed in theming QT Flatpaks. The system is in a dark theme but all the QT Flatpaks are using a light theme. I tried a bunch of overrides ans exposes the .themes folder in my home after copying all the themes. Nothing seems to work. Did anyone succeed in theming these apps in a...