No binding overwrite, but binding overwritten

import QtQuick 2.0
import QtQuick.Controls 2.15

Rectangle {
    id: rect
    width: 100
    height: 100
    color: "red"

    property bool flag1: {
        console.log("set flag1 to", cfg_flag1);
        return cfg_flag1;
    }
    property bool cfg_flag1: true

    Text {
        anchors.centerIn: parent
        text: "flag1: " + flag1.toString() + ", cfg_flag1 " + cfg_flag1.toString()
    }

    Timer {
        id: timer
        interval: 1000
        repeat: false
        onTriggered: {
            console.log("timer trigger");
            cfg_flag1 = false;
        }
    }

    Button {
        anchors.top: parent.top
        text: "button 1"
        onClicked: {
            console.log("button 1 clicked");
            let temp = cmpBinding.createObject(rect, {
                "target": rect,
                "property": "flag1",
                "value": true,
                "restoreMode": Binding.RestoreBinding,
            });
            temp.Component.onDestruction.connect(function() { console.log("destroyed"); });
            temp.destroy();
            console.log("end of clicked");
            timer.start();
        }
    }

    Button {
        anchors.bottom: parent.bottom
        text: "button 2"
        onClicked: {
            console.log("button 2 clicked");
            cfg_flag1 = true;
            cfg_flag1 = false;
        }
    }


    Component {
        id: cmpBinding

        Binding {
        }

    }
}