A 'Sun' lamp is so called because it simulates the light of the sun as perceived on Earth.
Its rays are parallel, from infinity. It has no position, and so no falloff with distance. (Good for you, in that respect.) The position of the lamp's gizmo has no bearing on its effect; only its direction makes any difference. All objects will cast shadows on other ...
Somehow, your camera is showing a negative scale transform.
Swipe the camera's 'Scale' fields in the Item tab and set to 1.
Readjust the camera using its internal settings (Focal length, or Lock Camera to View, etc)..
Maybe even swipe the padlocks next to the camera's scale to lock it off. You need special reasons to alter it.
If you just want to remove the color from the World Environment, but keep the lighting strength in B&W, place a RGB to BW Node between your HDRI texture and the Background Node of your world shader:
If you want to keep the HDRI colors, but still have only white lighting, mix a regular background with the black and white background, using the "Is ...
You can simply bake the light/shadows and then use them as a mask.
Bake a Combined Pass (default settings work fine)
Use the resulting BW texture as a mask for a MixRGB node
Have some tan Suzanne...
Something like that generates Sun light.
You can try to get rid of by Shadow - Cascade Shadow Map - Max Distance, but seems to be a tricky solution.
This effect is such visible when Lamp light is switched to Sun where Strenght of light is too high (1000). Lower value to 3 is ussually fine in most cases.
Later I noticed - light still penetrates the ...