I have a new computer with Windows 11 (and thus the infamous 24H2 update), Ryzen 9800X3D and RTX 5080 (also with newest available driver) and my game looks like this:
I have no mods installed (yet) and I have verified the integrity of game files via Steam. This happens at least when starting a fresh game (I don't have any pre-existing saves to test with). Trying different graphics settings hasn't helped, but I might have missed something there. I also seem to have exactly the same issue with Victoria 3 (thread) too on this computer.
I played a few months (in debug mode) and the attached .zip contains all the logs from that run, settings file and DxDiag.txt.
I had no issues on my previous Windows 10 machine, but of course this new one is a completely different computer with different parts, different OS and even (I think) slightly different GPU driver version...
Also, since this might be a common engine-level issue and not CK3 (or Victoria 3) specific, feel free to merge, move or whatever this or the V3 thread. Maybe I should download EU4, HoI4 and Stellaris too and check how they look. This far I've only tried CK3 + V3 (which had issues) and Cyberpunk 2077 + Nvidia Pendulum G-sync demo (which had no issues) on this computer.

I have no mods installed (yet) and I have verified the integrity of game files via Steam. This happens at least when starting a fresh game (I don't have any pre-existing saves to test with). Trying different graphics settings hasn't helped, but I might have missed something there. I also seem to have exactly the same issue with Victoria 3 (thread) too on this computer.
I played a few months (in debug mode) and the attached .zip contains all the logs from that run, settings file and DxDiag.txt.
I had no issues on my previous Windows 10 machine, but of course this new one is a completely different computer with different parts, different OS and even (I think) slightly different GPU driver version...
Also, since this might be a common engine-level issue and not CK3 (or Victoria 3) specific, feel free to merge, move or whatever this or the V3 thread. Maybe I should download EU4, HoI4 and Stellaris too and check how they look. This far I've only tried CK3 + V3 (which had issues) and Cyberpunk 2077 + Nvidia Pendulum G-sync demo (which had no issues) on this computer.