Spawning prop_dynamic in game (sourcemod) causes prop to be flashing at distance

I am spawning a prop_dynamic with a custom model. however when I am at a certain distance the prop seems to like become darker and brighter in some sort of sin wave. This also happens when standing completely still (camera as well!).
I've tried using a stock model (like a crate) but no difference.

Any idea would be great!
Cyba_Mephisto

EDIT: It seems to be a map issue since it happens with my player model as well when I am in third person. Any ideas?