I think it's really confusing if UHD devices like 4k monitors and smartphones get listed under visitor devices with the "wrong" resolution. As stated in #10296 it does make sense from a website point of view but in this way you can't differentiate between HiDPI devices and normal devices. E.g. it could be worth or necessary to provide images on a website with higher resolutions if more and more users with HiDPI displays are going to visit a website. With the current state this could not be tracked.
A solution could be to simply record both, the real screen resolution, which should also be presented under the device informations, and the "actual" resolution / viewport size.
A devicePixelRatio report could be good as well 👍