Broken images on iphone

You either upload or convert your images after upload to webp format, which is supported by limited range of browsers (see https://caniuse.com/#feat=webp for complete list). The important information for you is that it’s not supported in iOS Safari

I suggest you re-upload your media in other image format (jpeg, png etc.). If you want to swap one for one for example from Media tab of your admin area, you could try plugin such as Enable Media Replace