I have tried this on an Apple MacBook.

It's fine when viewed on Chrome or Opera, the problem exists on Safari.

I tried it also on an iPad with Safari and again the problem is there, but it is also there on Chrome too on the iPad.

On IOS Chrome uses Apple's webkit to render pages, so I suspect that is the common factor - Apple webkit.

Given that this is an issue for that picture but not others, there's something about it that is causing the issue.

Of course there shouldn't be an "issue" at all.

If you can isolate a test case that would be good to use with a bug report for further investigation.