Inconsistent binding behavior

import QtQuick
import QtQuick.Window

Window {
    id: window
    width: 320
    height: 320
    visible: true

    readonly property var globalPos: {
        window.x;
        window.y;
        return contentItem.mapToGlobal(0, 0);
    }

    onGlobalPosChanged: console.log(globalPos.x, globalPos.y)
} 

     readonly property point globalPos: { // only changing property type
        window.x;
        window.y;
        return contentItem.mapToGlobal(0, 0);
    }

     readonly property var globalPos: {
        window.x;
        window.y;
        const p = contentItem.mapToGlobal(0, 0);
        return { x: p.x, y: p.y };
    }

    function unused_reference() {}

     readonly property point globalPos: { // only changing property type
        unused_reference(window.x, window.y);
        return contentItem.mapToGlobal(0, 0);
    }