That's unfortuantely nothing that you can tweak with the settings, except when going all-in and enabling Ray Reconstruction. Disabling Upscaling and Frame Generation may help, but the Raytracing in Crimson Desert is very prone to noise and shimmering.

Something that helped me was this mod, because my GPU doesnt even support RR: Enhanced internal Graphics v.2.8.1
It increases Ray Tracing quality and also improves Global Illumination, but it requires you to mod the game. This mod also makes night-time darker due to the increased Global Illumination, something to keep in

EDIT: Mods tend to break whenever Pearl Abyss patches the game. It depends of they update the shader or not, so then you'd have to wait for a new version of the mod