Apple updated the design of the web version of the App Store. The Macrumors edition drew attention to this.
The updated App Store does not have new features. The descriptions previously located on the side moved down, a special emphasis was now placed on the reviews, and above the application names appeared dies, which remind that store applications are only available for devices with iOS.
Old version of App Store
New version of App Store
If the application is optimized for the screens of the iPhone X, then the preview will show screenshots on the smartphones of this model.