@danialbehzadi @blogs
You can try to modify environment variables settings
`QT_QPA_PLATFORMTHEME=kde QT_QUICK_CONTROLS_STYLE="org.kde.desktop" `
I would add it into
`/var/lib/flatpak/exports/share/applications/uk.co.piggz.amazfish.desktop`
My guess is that some package (something like plasma-integration) is not installed.
Please let me know if you figure out how to fix this.