GM has published technical service bulletin in March 2023 titled “Rapid Rear Brake Pad Wear” (21-NA-089) and it acknowledges the rear brake problem in 2020 - 2021 Chevrolet Silverados and mentions that they are now installing a shield to prevent road grime build up a calipers. Concludes that it’s not a safety issue so no recall, but essentially recommends that customers wash their brakes and it’s customer maintenance? It a new maintenance recommendation, but not included in the service manual! Strange as GM does not spend money on an engineering change if there isn’t a problem. Now you need to replace rotors with every brake job! Could calipers be next!