I cannot locate the link but there can be precision issues when using Large World Coordinates and Absolute World Position. Essentially, the further you get from the origin [0,0,0] the less-precise things can be, especially when far away.
Using Camera Relative World Position (pick the node, it’s on the details panel), can help correct this. It basically creates the math centric to the camera and not the world, avoiding the precision issue. Since you almost never see so far from the camera to run into a precision issue wheres with absolute coordinates you can still travel around the level to get to such a state.
If you are using distance-based effects for grass, etc, try using camera-centric:
NO IDEA if this is the root cause, but worth a try. And FWIW IIRC using camera-centric cuts down on large-world coordinate conversions, the LWC numbers you see on the bottom of the material. Smaller #'s there just = better. So in some-cases you might just-want for this, GL!
EDIT: This isn’t it but does speak to some of what I wrote above: Large World Coordinates Rendering in Unreal Engine 5. | Unreal Engine 5.5 Documentation | Epic Developer Community