I can't get this to happen on iOS (17.3.1) Safari either in the Codepen view or the debug view of Codepen (without an iframe) any particular device/version you see this happening?
Side note you can also use .from() instead of .to() tweens that way you don't have to set custom CSS for your second and third image and just let GSAP handle all the setup. I've also written a guide how you can create these kinds of card stacking effects and the logic behind it. You already got the logic down, but maybe it helps you when you want to start making loops or use staggers
This demo from the post looks like your setup. Hope it helps and happy tweening!
https://codepen.io/mvaneijgen/pen/MWxgQbV