Have you ever cleaned your intercoolers?
 

I was replacing upper control arms today, and to do so you have to take off the inner liner. I think its about 3 years ago since I cleaned the intercoolers last time, and this is how it looked today on the left side (didn't bother to take photos from the other side).

Before

https://neshaug.files.wordpress.com/2019/07/before.jpg

After

https://neshaug.files.wordpress.com/2019/07/after.jpg

....so, have you?

I have not seen left side on mine but when I was near right side it was cleaner without cleaning than yours after cleaning. It looks like you have a leak somewhere as it's all oily and dust sticks to the oil. Mine is all dry, no sign of oil anywhere undar car so I expect other side is fine too.

Could be a leak, could also be road conditions in Norway - especially if both sides are the same?