Unable to answer "What’s the surface here?" – Baseball Field – https://osm.org/way/165363340 via StreetComplete 58.1:

Mixed gravel and grass surface. StreetComplete doesn't want me to say "unpaved (generic)" because it wants me to split the area. But that's impossible in the app since it's an area (also, doesn't seem desireable? It's a baseball field, why separate the track from the green?) Making a note here and answering with Unpaved.