With the following code:

#include <QApplication>
#include <QWebEngineView>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QWebEngineView w;
    w.setUrl(QUrl("https://web.whatsapp.com/"));
    w.show();
    return a.exec();
}

I get an invalid chromium version from WhatsApp Web (see attachment)

The doc says "This version of Qt WebEngine is based on Chromium version 77.0.3865, with additional security fixes from newer versions." so there shouldn't be any problem.