This snow on runways and taxiways was answered on the March 23, 2022 Q&A:
Will snow be removed from runways of large international airports? In real life, runways are kept clear of snow. - Q&A Timestamp
Seb - Currently, snow is entirely procedural. Depending on the runway, if it is too thick, it even holds on runways. It is supposed to be like snow that has been rolled over/flattened. We have not tuned airport-by-airport: We did a global snow layer tuning and some airports have a lot more because it’s the way the runway looks. We simulated that dark surfaces receive more heat from the sun, and from the environment in general, so snow melts faster on dark surfaces. So airports with very bright runways (sometimes because it’s not tarmac but concrete) or just because the aerial is brighter, they will have more snow. So that’s something we need to rework to get runways completely without snow. I would say that’s only true on large airports. On our small airfield, when it snows, they don’t. They don’t immediately remove the snow, or even at all.