There should be a color filter setting in the darkvision section of a sheet, for example the most common form of darkvision found in D&D 5e is grayscale as creatures can't discern color but only see in various shades of grey, similarly fire genasi only see in shades of red. So for immersion's sake and reducing the power of darkvision at least in D&D 5e having a monochrome would be nice.