[Brightcolours]

Specular highlights don't really have 3D-properties. This test just makes clear how mechanical vignetting affects bokeh "ball" shapes ("cats eye", mirrorbox mechanical vignetting even), and that can also give a clue to the tendency of a lens to cause "swirly bokeh".

I think it makes a difference wether a highlight is close or far in relation to the focal pane, in size and in gradient. That's what I meant with 3d situation.

That is true for every bokeh related thing, for sure. And for sharpness measurements, LoCA, astigmatism, coma, and so on. And most probably also for vignetting. And LaCA.