Not a PNG file!

After capturing the iPhone screen I share sending to my email. is saved in PNG, but when I try to open it in Photoshop, it tells me "This is not a PNG file" Even though it shows an extension .png

If I rename the extension to jpg, then I can open it. I think for some reason, the iPhone share screen adds the wrong extension to the captured screenshot, why?

Going into the photo application and sharing from there it adds PNG, but this time I can open it in the photo editing app.

Any solution? Thanks.