A shape drawn by a widget using QPainter is not deleted when the widget is deleted

I have developed a widget that draws a circle using QPainter.  The test program creates the widget and then deletes it after 5 seconds.  But the circle it drew remains.  Shouldn't it disappear, or if not, how do I remove it (calling update() on the parent window has no effect)?

(I am using PyQt6 rather than PySide.)