Screenshots made on an iPhone XR are not accepted for 6.5 inch screenshots on App Store Connect

I just bought a new iPhone XR so I could make the screenshots for my App Store app. Starting March 27th 2019, you need to provide 6.5" (new phone models) screenshots:

However, App Store Connect is not accepting my screenshots made with this device. After further research, I found out that iPhone XR is actually 6.1":

I am not from the iOS world (I mainly work with Google and Android), so I am wondering if I am missing something, or are the docs wrong?

The iPhone XR and iPhone XS Max are the same size: 414x896. The reason your screen shot is coming out the wrong size is that the iPhone XR is double resolution, where as the iPhone XS Max is triple resolution. But that's not a problem. If your screen shot is coming out as 828x1792, just run it through any basic image-munging app, such as Preview, and change the size to 150% of its current size:

 828 * 1.5 = 1242 
1792 * 1.5 = 2688

That gives you the required size, 1242x2688.

(Note, however, that you do not need any device merely in order to generate a screen shot acceptable to the App Store. Screen shots from the various Xcode Simulators will do just fine. Even an app that has functionality that doesn't quite work on the Simulator can be tweaked to generate its normal interface so that you can take the screen shot. I have nine apps currently on the App Store, each with an accepted set of screen shots, and not one of those screen shots was taken on a device.)