Would you say the picture below (by A. S. Shevchenko) is almost like an optical illusion?
Have you seen any pictures or sights that fooled your brain for a moment but that you wouldn't call optical illusions, and if yes, what is the salient difference?
It's one of those ambiguity things of which this is the canonical example.
It's also similar to this image:
https://i.pinimg.com/736x/60/16/5b/60165bfd56829bb95563a36cd69a5825--art-optical-optical-illusions.jpg
It's difficult to see it as anything until it "snaps" and then it's impossible to not see it.