Both the front and rear factory "mud flaps" aren't any such thing. Frankly I'm not sure why they bother to put them on as they really don't block anything. I put WeatherTech no-drill mud flaps on my 2018 and were very happy with them. Because of my past experience with WeatherTech, I picked up another set for my 2021 Chevy 3500. The install is as simple as could be, just remove the three screws from the factory flap, slide the WeatherTech onto the factory flap, then put the three screws back in. The WeatherTechs give you 6" of additional rock chip stopping mud flaps for $40 and take about 5 minutes to install. What's not to like?
Mud Flaps - Laser Measured Splash Guards for Trucks & SUV's | WeatherTech
Custom-fit, no-drill Mud Flaps protect your vehicle's fenders and exterior from rocks, mud, road grime and other debris that can cause damage over time.