My previous system also had this issue, it is a bit weird so i will do my best to explain.
It happens when i turn kodi menu resolution at 4k (4096x2160p) at 100 refresh rate. Which was also the resolution the system picked after installing. As far as i knop this resolution is only for the Kodi menu right?
The weird thing is when i leave the Kodi menu on for a while, the screen turns black now and then for about two seconds. Also i see a bit of a horizontal green line. Most of the time when i start a video this stops (also 4k). Something is happens a lot and sometimes only one time, it seems really random. I haved check the cpu/gpu temp, that is not the problem.
When i dial the resolution back 1920x1080p at 100 refresh rate. This problem goes away. My tv is a LG Oled E9.
Any ideas why this happens?