QWebEnginePage::certificateError(const QWebEngineCertificateError& certificateError)

in Qt5 it was virtual function which can be re implemetned to return true to ignore the error and complete the request. Return false to stop loading the request.
But in Qt6 it is turned as Signal instead of virtual method and parameters are const, so can not call acceptCertificate() or rejectCertificate() because both of it are non const function.