Removing Banners in FullScreen Mode

Question

class Win(PyQt5.QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__() 
        #self.setWindowFlags(PyQt5.QtCore.Qt.WindowCloseButtonHint | PyQt5.QtCore.Qt.WindowType_Mask)
        self.showFullScreen()
        #self.setWindowState(PyQt5.QtCore.Qt.WindowMaximized)
        '''
        self.setWindowTitle("TestWindow")
        self.setStyleSheet("""
                    QMainWindow{
                        background-color: #212121;
                        color: #d50000;
            """)
        '''
        self.banner()
        self.show()

    def banner(self):
        flair = PyQt5.QtWidgets.QLabel('TestWindow', self) 
        flair.setStyleSheet("""
                            QLabel{
                                background-color: #d50000;

                            }
                        """)
        flair.resize(500,500)
if __name__ == "__main__":
    app = PyQt5.QtWidgets.QApplication(sys.argv) 
    w = Win() 
    sys.exit(app.exec()) 

IMAGE =

For some reason if I set my window maximized it works fine and I can display labels however as soon as I set it as fullsized it doesn't allow me to include any labels at all, whats the solution to this?