[REG 6.8.1->6.8.2] QML color dialog uses wrong button style

Consider the following QML code

import QtQuick
import QtQuick.Dialogs
import QtQuick.Controls

Window {
    visible: true

    Button {
        text: "Click me"
        onClicked: colorDialog.open()
    }

    ColorDialog {
        id: colorDialog
    }
} 

and run it in qmlscene on KDE Plasma.

The "Click me" button follows the system theme as expected. The footer buttons in the color dialog however look completely different and out of place.

See screenshots in https://bugzilla.redhat.com/show_bug.cgi?id=2344793