Mountainmen eat more supply in mountains rather than less?

[Soar]

The listed food usage in the tooltip for units with the Mountainmen trait is higher when they're in mountains compared to other terrain, rather than lower like it is supposed to be. See the image below. It shows two tooltips for the exact same unit, first when it is in the mountain region of Nicaea and then while in the plains region of Massilia. The food usage in the first case is higher. Units without a corresponding trait don't seem to increase their supply usage in the same terrain.