How to display (custom) icons for pageActions linked to a QWebEngineView in PyQt6?

Question

After upgrading to PyQt6, pageActions are now shown as text instead of icons. How do I get them to show as icons again? Is it possible to define custom icons instead?

Code to reproduce is given below.

import sys
# pageAction with icons
from PyQt5.QtWidgets import QWidget,QToolBar,QVBoxLayout,QApplication
from PyQt5.QtWebEngineWidgets import QWebEngineView,QWebEnginePage

# pageAction with text
# from PyQt6.QtWidgets import QWidget,QToolBar, QVBoxLayout, QApplication
# from PyQt6.QtWebEngineWidgets import QWebEngineView
# from PyQt6.QtWebEngineCore import QWebEnginePage
        
class Example(QWidget):

    def __init__(self):
        super().__init__()
        vbox = QVBoxLayout()
        self.setLayout(vbox)
        self.webEngineView = QWebEngineView()
        self.toolBar = QToolBar()
        self.toolBar.addAction(self.webEngineView.pageAction(QWebEnginePage.WebAction.Back))
        vbox.addWidget(self.toolBar)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Example()
    ex.show()
    sys.exit(app.exec())