[Reg 5.15.2/6.3.2 -> 6.4.x] DropShadow: Changing radius at runtime also changes Z-order

import QtQuick
import Qt5Compat.GraphicalEffects

    width: btn.width + 50
Window {
    height: btn.height + 50
    color: "silver"
    visible: true

    Rectangle {
        id: btn
        anchors.centerIn: parent
        color: mouseArea.pressed ? "midnightblue" : "darkblue"
        width: 100
        height: 50
        radius: 4

        Text {
            anchors.centerIn: parent
            color: "white"
            text: "Click Me"
        }
        MouseArea {
            id: mouseArea
            anchors.fill: parent
        }
    }
    DropShadow {
        id: lowerShadow
        anchors.fill: btn
        source: btn
        color: mouseArea.pressed ? "lightgray" : "gray"
        radius: mouseArea.pressed ? 0 : 3 // Making this a fixed value causes the problem to disappear
        transparentBorder: true
        verticalOffset: 3
        horizontalOffset: 3
    }
}