grabToImage: wrong image resolution with high dpi scaling

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.3

import QtLocation 5.9
import QtPositioning 5.8

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

    Map {
        id: map
        anchors.fill: parent

        plugin: Plugin {
            name: "osm"
        }
    }

    footer: Button {
        text: "Popup"

        onClicked: map.grabToImage(function(result) {
            result.saveToFile("/storage/emulated/0/DCIM/something.png");
        });
    }
}