On an iOS device, long pressing on a regular div fires two events: a touchstart, and then a touchend when the finger is released. Long pressing on an img element, however, fires three events: a touchstart, then a short while thereafter a mousedown, and finally a touchend. I've written up a trivial example to show this difference at https://codepen.io/JarodG/pen/zYKMeaJ I'd expect that, with -webkit-touch-callout disabled (which prevents the image preview / save callout) the long press behavior would be the same between these two elements, especially since a regular tap fires the same events for both.
<rdar://problem/73475898>
On the iOS 14.4 beta I see only touchstart and touchend. If I hold the tap long enough I also see touchmove events but that occurs on both the div and the img element.
I’m still able to reproduce this on iOS 15.1 on my device.