*UPDATED WITH SCREENSHOTS*
If you look into the direction of the sun, with the sun still in the viewport, you'll see the scene in front of you being lightened accordingly.
But if you look down to the ground or zoom in, so that the sun is out of the viewport, you'll notice that the according lighting disappears together with the sun and the scene gets darker immidiately.
That should not be the case, the lighting of a scene should depend on the available light sources, independent on wether the player sees them or not.
*Notice*: Some people in the comments say, that it's not the lighting that changes, but rather an overlay effect due to sunflare. Even though they might be right, i still think it's rather disturbing, than improving immersion, because the change in brightness of the environment is to significant. I never experienced this in real life and apparently it led me to the conclusion, that this is a bug, opening this ticket. so it might could be called a "misfeature", as someone in the comments stated.