Currently the Webpopup for places states that the data is from geonames.org. This is only correct for the cities.

By default the attribution should not be shown for all placemarks. Only exception are:

• cities (attributed to geonames.org as done right now)
• nations (attributed to the "CIA World Factbook", linked to https://www.cia.gov/library/publications/the-world-factbook/ )