Windows inactive accent colour changes when window loses focus

This doesn't match the behaviour of e.g. a native Switch whose background follows the accent colour, as its background colour will remain unchanged when the window loses focus.

To reproduce, run the following snippet (after applying https://codereview.qt-project.org/c/qt/qtdeclarative/+/501482) and then open another window to make the Qt Quick window lose focus. The expected behaviour is that the Rectangle stays the colour it was (the accent colour) after the window loses focus. The actual behaviour is that it becomes #f0f0f0.

import QtQuick
import QtQuick.Controls

ApplicationWindow {
    id: root
    width: 400
    height: 400
    visible: true
    title: rect.color

    Rectangle {
        id: rect
        implicitHeight: 32
        implicitWidth: 32
        color: palette.accent
    }
}