If I set the scale value (150) to roughly the ppi of my screen (4k 27"), I can see the effect.
You should see the rotating stars only in a small field of view (fov) where your eyes are focused and all other stars should seem to remain still.
My phone screen is a bit over 500 ppi. I tried it full screen across the entire range that it's in focus (I'm mildly nearsighted), and I could just see the things spinning across the whole field if the pinwheels were big enough to see motion at all.
Maybe it doesn't work on small/AMOLED screens?
Try it in full screen, if you did not.
> What effect am I supposed to see?
I can see only a tiny area in the center of my vision animate (at default scale). The larger the scale, the bigger the area.
So for me either the stars are too small to see any motion, or I can see them all spinning no matter what.
What effect am I supposed to see?