Huh. So, according to the other comments, if they'd set the `accepts` on their form to MIME types instead of extensions, the browser would have converted the file to a JPG automatically.
Which means I think the blame is more on Apple side since the 'accept' attribute is intended to work with any 'Unique file type specifiers' [1] which includes both MIME types and extensions. Perhaps Apple is following a different RFC?
[1] https://developer.mozilla.org/en-US/docs/Web/HTML/Element/in...