MSFS uses meteoblue snow depth data.
I think they are using a low zoom level to minimize data quantity over the network. If you look at the snow depth map on meteblue over NZ and zoom in/out, you will see a point where the snow coverage goes over a very large region.
You can see that here: https://www.meteoblue.com/meteo/cartes/#coords=4.74/-44.01/171.15&map=snowDepth~hourly~auto~sfc~none
Same problem with Innsbruck for example where the granularity doesn’t show the fact that there’s no snow in the valley.