Qt networkproxy how to determine proxy anonymity level?

Question

Qt

What are the ways to determine the level of proxy anonymity (Transparent, Anonymous, Elite)
I make a simple request:

manager = new QNetworkAccessManager(this);

QNetworkRequest request;

    request.setUrl(QUrl("https://www.google.com"));

    request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");

    reply = manager->get(request);
    
    QNetworkProxy proxy;

    proxy.setType(QNetworkProxy::HttpProxy);
    
    proxy.setHostName("proxy.example.com");
    proxy.setPort(1080);
//  proxy.setUser("username");
//  proxy.setPassword("password");
    QNetworkProxy::setApplicationProxy(proxy);

connect(reply, SIGNAL(readyRead()), this , SLOT(finishedRes()));

void Dialog::finishedRes()
{

}

Answer 1

proxyjudge

Answer 2

Hack some large bank through it, if after that you don’t lie face down on the floor, then the proxy is anonymous.
And how else to understand that a proxy is leaking information about you to third parties, while no one needs you, there is no way to check it.

Answer 3

You can check the presence of the X-Forwarded-With header, but if you go to https sites, then don't care what proxy.