iPhone 8 Plus has weird screenshot/display dimensions

Hello apple crowd!

I'm developing an app and want to differentiate between the iphone model specific display dimensions and and dpi value. Works fine for every user and model ... except my business partner who is using an iPhone 8 Plus.

She sent me a screenshot in portrait mode and it has a dimensions of 576x1024px. I have no idea how the dimension can be so weird and doesn't fit the 414x736px with 3x scale factor or 1.242x2.208px.

She has no weird system settings whatsoever. Does anybody of you have an idea what this issue can be related to?

Thanks a lot in advance!