QML garbage collector doesn't work correctly with Loader

import QtQuick 2.12
import QtQuick.Controls 2.12

Item {
    id: root
    width: 600
    height: 600
    
    Loader {
        id: loader
        anchors.fill: parent
    }
    
    Button {
        text: "ClickMe"
        anchors.centerIn: parent
        property int imgIndex: 0
        onClicked: {
            imgIndex = 0
            loader.setSource("Collage.qml", {index: ++imgIndex % 4})
            gc()
        }
    }
}

import QtQuick 2.12

Image {
    width: 500
    height: 500
    property int index: 0
    fillMode: Image.PreserveAspectFit
    source: index + ".jpg"
    cache: false

    Image {
        width: 300
        height: 300
        anchors.centerIn: parent
        fillMode: Image.PreserveAspectFit
        source: index + 1 + ".jpg"
        cache: false
        Image {
            width: 100
            height: 100
            anchors.centerIn: parent
            fillMode: Image.PreserveAspectFit
            source: index + 2 + ".jpg"
            cache: false
        }
    }
}