RESEARCH: 4K compatibility!
The claim of 4K compatibility is very deceiving. 4K, or UHD resolutions, most commonly, in the consumer market, at 3840x2160 resolution, has been available since HDMI 1.4 specifications. Even 4K/60 has been a potential resolution since HDMI 1.4. So, when a display talks about 4K support, don't just assume you are getting the latest and greatest full bandwidth HDMI 2.0, 18Gb/s, UHD with HDR support from that display. You MUST do your homework. You must do the same for all devices that make such a claim as I have seen displays which seem to be very limited on their input resolution capabilities and have serious issues with 4K/60 support as it looks like they are limited to 10Gb/s data rates for video, not 18Gb/s.
This is especially irritating for HDMI cables or HDMI extension systems. Longer cables/distances have real issues with 4K.