For years, the standard photo file format has been "JPG" (pronounced jaypeg) but newer phones are using HEIC by default.
|Newer iPhones are starting to save photos in HEIC format|
There is an easy and quick solution - on the iPhone choose the option Settings|Camera|Formats and select "Most compatible". This changes the default format back to JPG.
For more info about the problem, click this link https://www.macworld.co.uk/feature/iphone/what-is-heic-3660408/ or contact our support desk.