Aperture and starburst effects

Thanks to Emily for these pictures that show a starburst effect for headlights and streetlamps. There are more details here https://www.slrlounge.com/diffraction-aperture-and-starburst-effects/ which says that it is to do with diffraction. I was wondering how a circular hole could produce radial diffraction but then I remembered how variable apertures in cameras work. Scroll down on this link to see pictures of how it is done https://www.veedyou.com/gopro-low-light/ The aperture is not circular but a series of flat edges. Each pair of parallel flat edges acts as a slit for diffraction if the aperture is small enough. The first link shows that starburst only happens for small apertures. Emily's pictures suggest to me that this aperture must have 16 edges.