When I add a new Layer named "cities" and apply a symbology for the cities by country, I get the layer name and the field used for the symbology in the legend.
The legend shows as follows:
cities (layer name)
cities (field name)
... (symbology)
The Layer Name can be renamed, so can the field name, but it is not possible to remove/hide the field name, which is redundant in cases like this. It would be great if we could hide the layer name and the field name when required.
This issue is described here as well: How to display no field heading text in the legend... - Esri Community
