Sorry for answering in English.

According to the wiki, an area/multipolygon with highway=pedestrian should be tagged with area=yes, seehttps://wiki.openstreetmap.org/wiki/Tag:highway%3Dpedestrian#Squares_and_plazas.

According to my understanding, this is important for routing, and indicates that pedestrians can move freely in all directions within the area, unlike for example in a building.