I have not prepared the soup myself, but here is a recipe that lays out step by step how to make Kübiscremesuppe:
Some restaurants buy locally grown pumpkins from nearby farmers at Naschmarkt in a from "farm to table" fashion. Knowing where ingredients are sourced adds an extra layer of flavor to the soup because you feel more connected to the very pumpkins you're eating. As I mentioned before, pumpkin soup is also seasonal so there is a connection to the change in weather which locals try to take advantage of.