Good on you for including the subpixel matrix photo as usual. But we really need to do a better job at explaining the problem here. This is a WR/GB display, which cannot resolve the full 3840(RGB)x2160 resolution. This serves as a trick to consumers, because this is either omitted or not explained properly in product marketing, and now in this review of the product as well.
The display section should say "Our Fujitsu test unit is equipped with a 3840(WR/GB)x2160 display from LG." rather than "4K display", it should describe what the issue is, and the article should clarify this in the overview as well as the specs summary & display comparison columns.
Refer to this article, and to my comment in the comments section of the article for more information about this isssue. https://www.notebookcheck.net/Faux-K-Make-Sure-Your-Next-4K-Laptop-is-Actually-4K.289242.0.html