You got it too f you pay close attention.
Run the following sketch to see it:
void setup() {
size(1000, 1000);
background(0);
fill(255, 255, 255);
noStroke();
ellipse(500, 500, 100, 100);
noStroke();
fill(0, 0, 0);
ellipse(500, 500, 100, 100);
}
It is just that since it is bigger, it is way more subtle and if you don’t have such a high contrast as with the previous sketch, you don’t really see it.