• I use qt 6.7.2
• QQmlContext to inject context property
• Program works (meaning m_systemHandler's state is changing fine)

Main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQuickView>
#include <QQmlContext>

#include <controllers/system.h>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;

    System m_systemHandler;
    QQmlContext * rootcontext = engine.rootContext();
    rootcontext->setContextProperty( "systemHandler", &m_systemHandler );

    const QUrl url(QStringLiteral("qrc:/TeslaInfotainment/main.qml"));
    QObject::connect(
        &engine,
        &QQmlApplicationEngine::objectCreated,
        &app,
        [url](QObject *obj, const QUrl &objUrl) {
            if (!obj && url == objUrl)
                QCoreApplication::exit(-1);
        },
        Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

RightScreen.qml where injected class is used:

import QtQuick 2.15
import QtLocation
import QtPositioning

Rectangle {
    id: rightScreen

    anchors {
        top: parent.top
        right: parent.right
        bottom: bottomBar.top
    }
    color: "orange"
    width: parent.width * 2/3

    Image {
        id: lockIcon
        anchors {
            top: parent.top
            left: parent.left
            margins: 20
        }
        width: parent.width / 30
        fillMode: Image.PreserveAspectFit
        source: ( systemHandler.carLocked ? "./secured-lock.png" : "./unlock.png" )

        MouseArea {
            anchors.fill: parent
            onClicked: systemHandler.setCarLocked( !systemHandler.carLocked )
        }
    }
}

I assume this problem should either because of my ide configuration (it is default, just after installation) or this approach to expose a class is no longer a good way. I am following a guide on youtube which was recorded 1 year ago, so idk. If someone will provide resources to read that might help solving this, it would be really great!