Material.roundedScale does not propagate from parent item to child buttons

import QtQuick
import QtQuick.Window
import QtQuick.Controls.Material

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    Material.foreground: Material.Pink
    Material.roundedScale: Material.NotRounded

    Button {
        text: "hello"
        // this works here: Material.roundedScale: Material.NotRounded
    }

    Button {
        y: 200
        text: "hello2"
    }
}