Issue present for the past week or two on the latest and previous latest iOS versions. Likely unreliable to reproduce, but just experienced it here:
https://lemmy.world/comment/14264451
I tapped on the GIF, swiped down (… or up?) to close it, and the GIF zoomed in. From that point it’s difficult to close the GIF with one finger, but zooming out with two fingers works fine.
Might be a touch screen issue? Try a drawing or paint app and see if there are any anomalies while colouring in the screen.