I assume it’s used for location streaming, but I don’t know how invasive it is and if it can possibly be replaced. In any case I think that if you don’t enable location streaming there should be no problem. Anyway let’s wait to see if someone involved in the development of delta chat answers with more precision.
Delta Chat is using Mapbox tile server to show the map if you enable experimental “location streaming” feature and open the map. It is not used as long as you do not enable this feature or use it only to send your location but never look at the map.
Thank you for the clarification. It ends up working the way I expected and I personally don’t have any particular problems with it. In the future (though not necessarily as a priority) I think it would still be actually desirable to switch to services like osmdroid also to avoid any controversy.