Why does the electronic shutter prone to diffraction?

Question

According to some comparisons I've read between mechanical and electronic shutters, the latter is prone to the diffraction of light, how so?

Answer 1

No, it's the opposite, the edges of the mechanical shutter diffract light, while the electronic shutter is not affected because it does not exist; there is no physical element that might cause the diffraction.

The answer by chulster here shows that the effect is only noticeable in very high contrast situations, like bright light sources (similarly to the well known star-like diffraction from the lens iris).