Checking around the community, this issue has popped around from time to time, with different possible causes, and solutions. From what I could gather and test, please try the following:
If your scene has any post processing effects enabled, please disable them, or set them all back to defaullt settings
From the screenshots, I cannot confirm if you have an active skylight, if you don’t please add one, along with a simple, directional light
Change your Exposure to Manual (see the following guide)
Change your landspace material to a flat, simple base color, and test again
If your material is using World Position Offset, set it to zero
If everything fails, you can test by converting your landscape into a static mesh, for setting up your render
For further methods to test, please check the related threads below: