I'm your huckleberry...
It must have been programmed by the same people who programmed my car to tell me my tyre pressures are low every time I turn the car on on a cold day. Low pressure on all 4 tyres, no shit it's -4degC.speedo isn't doing anything its not stock. Its just that GM decided to be an idiot and give it a polling rate of like 2Hz. its 2020 already, no reason they can't do actual speed. it wouldn't cost them anymore, they just decided to go the stupid route with it.