From what we can see, there are Here maps appearing in the apps, but from what we have been told by reliable sources, Facebook is also using Here geocoding. The geocoding provides a significant amount of specific place data to both Facebook and users when tagging a location in Instagram, Messenger or in the main Facebook app.(…)
First, having good location technology to tag where a person is helps Facebook be a richer service for its users who may want to update their status or post pictures from specific locations, especially considering how big a part mobile plays in Facebook’s business today.