Hi @mondob, I haven't implemented this myself, but looking at the Mapbox documentation, it looks like there is such thing as a heatmap, but it's a different way to mark the map, more like zones rather than dots. There are also circle-emissive-strength and circle-opacity properties we could use if your data provides a reference to which mark is located within high density areas.
This example uses the property "ethnicity" to give color to a mark. If we could find a way to set another property for each object from your "mapCoordinates.data," we should be able to make this happen.