Well you really don't know what type of Orange Juice they are using, it could be a mix of oranges even. Different locations might use different varieties of orange.
Well heres the menu...https://www.ihop.com/en/menu/beverages/fruit-juices the juice looks yellow
They might be adding water, or the ice melted by the time they took the picture. It could also be that variety of orange that is responsible for the yellow coloring.