That was the same with me. I guess it is because the dots are already colored, thus leading one's focus towards the translation. However if you ignore the color

That was the same with me. I guess it is because the dots are already colored, thus leading one's focus towards the translation. However if you ignore the colors and imagine a 3-petal flower, then you can see the flowers rotate counter-clockwise. Try following the outer edges where the density of dots is sparse and less confusing to form a mental image of the petal.