I have started replaying the MSB today by redoing the Journey mode from the beginning. The run is called Heigenbruken - Gemunden Limited stops, the third scenario in chapter 1. This one starts in proper winter scenery and as you go down the scenery transitions towards all green foliage slowly losing the snow. During the transition, the trees render complete white at medium to high distance and once they get close enough to get picked up and rendered in higher quality, they switch color abruptly from white or grey to dark green. The trees ahead of me should be green in color as the ones near the locomotive are and once I got to the spot marked in the screenshot they too became green (magic?). I am not using any mod or engine file tweak, this is vanilla game rendering. This is towards the end of the transition but a minute before this the difference is even more visible as the trees close are dark green and the ones far are bright white!?