MaskedBlurItem is broken

import QtQuick 2.12
import EffectTest 1.0
import QtGraphicalEffects 1.12
import QtQuick.Studio.Effects 1.0
import QtQuick.Studio.Components 1.0

Rectangle {
    width: 1000
    height: 1000
    color: Constants.backgroundColor

    Image {
        id: bug
        source: "qrcode.png"
        sourceSize: Qt.size(parent.width, parent.height)
        smooth: true
        visible: false
    }

    Image {
        id: mask
        anchors.fill: bug
        source: "mask.png"
        sourceSize: Qt.size(parent.width, parent.height)
        smooth: true
        visible: false
    }

    MaskedBlur {
        anchors.fill: bug
        source: bug
        maskSource: mask
        radius: 16
        samples: 24
    }

    MaskedBlurItem {
        id: maskedBlur
        x: 500
        y: 0
        width: 500
        height: 500

        Image {
            id: image1
            x: 0
            y: 0
            width: 500
            fillMode: Image.PreserveAspectFit
            source: "qrcode.png"
        }

        Image {
            id: image2
            x: 0
            y: 0
            fillMode: Image.PreserveAspectFit
            source: "mask.png"
        }
    }

    Image {
        x: 0
        y: 500
        width: 500
        fillMode: Image.PreserveAspectFit
        source: "qrcode.png"
    }

    Image {
        x: 500
        y: 500
        fillMode: Image.PreserveAspectFit
        source: "mask.png"
    }
}