QOpenGLWidget - Glitch when drawing an ellipse with OpenGL-based QPainter

I am drawing an ellipse over some openGL render in a QOpenGLWidget.

The ellipse is drawn in QOpenGLWidget::PaintGL(). I enclosed my OpenGL commands between QPainter::beginNativePainting() and QPainter::endNativePainting() and everything works fine.

But when the ellipse is located in certain positions, with the center outside the viewport, an additional, unwanted ellipse is drawn at (0,0).

I tried to reproduce the bug in a QWidget, drawing my ellipse in QWidget::paintEvent(). But I did not manage to reproduce it, so I guess it is specific to QOpenGLWidget. I may be wrong of course.

Last thing worth mentioning (see attached example): the bug only occurs when using a QPen with a dash pattern after drawing my ellipse.