SUMMARY I draw an ellipse in a PDF with the following default setting: outer circle red, fill color blue. The ellipse is then visible. Then I right-click, select Properties and deactivate the fill color. I save in PDF. Unfortunately, the deactivation of the fill color is not saved. The ellipse is still blue Video: https://youtu.be/mDZvYT_VCuY
It's actually a poppler library bug https://gitlab.freedesktop.org/poppler/poppler/-/merge_requests/1492