QOAuthUriSchemeReplyHandler does not see proper Stage?

#define REDIRECT_URI "https://127.0.0.1:5476/"

class GoogleSSO : public QObject
{
   Q_OBJECT

   public:
      explicit GoogleSSO(QObject *parent = nullptr);
      virtual ~GoogleSSO();

   public slots:
      Q_INVOKABLE void authenticate();

   private:
      QOAuth2AuthorizationCodeFlow *google;
      QOAuthUriSchemeReplyHandler *replyHandler;
};

#include "oauth2_google.h"

GoogleSSO::GoogleSSO(QObject *parent) : QObject(parent)
{
   this->google = new QOAuth2AuthorizationCodeFlow(this);
      this->google->setClientIdentifier(...);
      this->google->setClientIdentifierSharedKey(...);
      this->google->setState(...);
      this->google->responseType() = ...;
      this->google->setAuthorizationUrl(QUrl(...));
      this->google->setRequestedScopeTokens(...);
      this->google->setTokenUrl(QUrl(...));

   QObject::connect(this->google, &QOAuth2AuthorizationCodeFlow::authorizeWithBrowser, this, [&](const QUrl &url) {
      qDebug() << "URL Built:" << url;
   });

    this->google->setModifyParametersFunction([](QAbstractOAuth::Stage stage, QMultiMap<QString, QVariant> *parameters) {
      if (stage == QAbstractOAuth::Stage::RequestingAuthorization)			// stage when building url just before opening the browser with the very first url
      {
qDebug() << "im in stage RequestingAuthorization";			// this works fine
        // The only way to get refresh_token from Google Cloud
	parameters->insert("access_type", "offline");						// Needed for Refresh Token (as AccessToken expires shortly)
	parameters->insert("prompt", "consent");							// Param required to get data everytime	
      }
      else if (stage == QAbstractOAuth::Stage::RequestingAccessToken)
      {
qDebug() << "im in stage RequestingAccessToken";			// replyHandler does not recognize it, however URL realy proper... so to my understanding QAbstractOAuth::Stage does not recognize this stage properly
	// Percent-decode the "code" parameter so Google can match it
	QByteArray code = parameters->value("code").toByteArray();
	parameters->replace("code", QUrl::fromPercentEncoding(code));		// need to fix the URL syntaxt to manage spaces
      }
      else {
qDebug() << "im in stage OTHER";
      }
    });


   // ERROR LOGIN
   QObject::connect(this->google, &QOAuth2AuthorizationCodeFlow::authorizationCallbackReceived, this, [&](const QVariantMap &data) {
      QString error = data.value("error").toString();
      if (!error.isEmpty()) {
         qDebug() << "ERROR";
         replyHandler->close();
      }
   });

   // SUCCESS LOGIN
   QObject::connect(this->google, &QOAuth2AuthorizationCodeFlow::granted, this, [this]() {
      qDebug() << "SUCCESS";
      replyHandler->close();
   });
}

// Invoked externally to initiate
void GoogleSSO::authenticate() {
   replyHandler = new QOAuthUriSchemeReplyHandler(QUrl(REDIRECT_URI), this);    // or this->google instead of this?
   replyHandler->setRedirectUrl(QUrl(REDIRECT_URI));
   this->google->setReplyHandler(replyHandler);

   if (replyHandler->listen()) {
      qDebug() << "STARTNG TO LISTEN";
      this->google->grant();   // Initialize OAUTH2 Workflow
   }
   else { qDebug() << "ReplyHandler ERROR"; }
}

// Destroy
GoogleSSO::~GoogleSSO()
{
   //replyHandler->close();   // causes crash as during closing of app, because replyHandler doesnt exist anymore, therefore calling null pointer
   delete this->google;
}