Hello. I can explain. At some recent time, Lemmy.zip started to proxy images as AVIF files. AVIF files currently are not well supported on Android (not sure about iOS) so a lot of images fail to load using the Android built-in decoder. Usually the browser is fine because it uses a custom decoder. (Actually for this particular image, even Chrome is having a hard time on my end)

But yeah, this is a problem with lemmy.zip and not any of the other instances.