SwipeView.contentItem behaves differently compared to Qt

import QtQuick 2.15
import QtQuick.Controls

Rectangle {
    width: 800
    height: 480

    SwipeView {
        id: view
        anchors.fill: parent

        // comment out this part when using the regular Qt
        contentItem: Flickable {
            id: flickable
        }

        Rectangle {
            width: 200
            height: 100
            Text {
                anchors.centerIn: parent
                text: "First"
            }
        }

        Rectangle {
            width: 200
            height: 100
            Text {
                anchors.centerIn: parent
                text: "Second"
            }
        }

        Rectangle {
            width: 200
            height: 100
            Text {
                anchors.centerIn: parent
                text: "Third"
            }
        }
    }

    Text {
        font.pixelSize: 24
        anchors.bottom: parent.bottom
        anchors.horizontalCenter: parent.horizontalCenter
         // replace this with view.contentItem.movingHorizontally when using the regular Qt
        text: flickable.movingHorizontally ? "<->" : "..."
    }
}