Looks like Mario Kart 8 Deluxe has lost one feature the Wii U version had. People are noticing that the Mii faces in Mario Kart 8 Deluxe just don't show the range of emotions they did in the Wii U version. Mii faces in the Switch version seem to remain the same during the entire race, whereas on Wii U, they would react to what was going on with your character. Could be a bug, or could be removed content. Either way, it can be a bit creepy!