That might be it. I use dirt effects in the freestyle station, do you notice changes with and without the shader enhancement? If not, check out the materials with "concrete" or "earth" in their name. Otherwise, I also have the problem and my solution is to do nothing about it :-)

Haha I wanted to do nothing, for sure! But it was rendering my ballast track way too dark. And that is actually one of the issues that another ballast mod has, that mine was intended to correct. I mean it's the original reason I started the mod (before it grew to include other things).

Yes it affects yours too. I added 2 screenshots to that Google Drive link if you want to compare. The darker one is with the shader mod. The difference is not severe, it's similar to vanilla buildings, so your multiply/linear burn settings are probably not very high. Those make it worse. (Unrelated, I just noticed the small building has a different roof on era A platform than era B. Neat!)

I originally tried using dirt/rust maps, but for some reason I couldn't get them to work. I added both dirt and rust maps, plus their normal maps, and the dirt/rust section (with "age" cranked to 1.0 for a static asset), and I set the material type to one that supports dirt/rust (tried both the cblend and non-cblend versions), and no matter what I did I could not get a useful effect to appear on the material 🤷‍♂️

Then I tried op maps, similar to how the vanilla stations/buildings use it. If set to Overlay, the rendering is very close with or without the shader mod. It looks like the overlay texture has a different position or orientiation, but otherwise seems the same.

But if I use Multiply or Linear Burn, which are more "severe" operations, the shader mod renders dark, sometimes very dark. Because I'm applying dirt/rust to lighter textures, I need to darken them a lot, so my settings are quite high, which seems to make the shader mod issue much worse.

Thanks!