Truck moving at rocket speed in reverse w/o pressing accelerator

I have a 2021 Freightliner Cascadia. For about the past week or so, when I am doing a back, and I put the transmission in reverse, I ease off the brake and I don't touch the accelerator at all, the truck will lurch backwards like a rocket. I used to be able to back into a (tight) parking spot at a truckstop slowly and gently. Now the truck wants to move backwards like a rocket when I ease off the brake, and if I press the brake again to try to slow the truck down, it is hard to slow the truck down without just stopping the truck altogether. So, frequently, when I try to slow the truck down (without trying to stop the truck), the truck will violently come to an abrupt stop.

I don't notice the truck's engine moving too fast forward when I am driving forward with the transmission in drive. Now I know that it doesn't make sense for the truck to move excessively fast without pressing on the accelerator in reverse but not seem to move excessively fast without pressing on the accelerator in drive, but that is what it seems like it is doing.

Before about a week ago, my truck would only move about 1 mph in reverse on flat ground if I did not press the accelerator or the brake pedal. Now, my truck moves about 5 mph in reverse on flat ground when I don't press the accelator or the brake pedal.

Does anyone know why in the last week or so, my semi-truck started moving in rocket speed in reverse without my even touching the accelerator at all?

 

My truck has an automatic transmission.

 

I will definitely try that. That might be what is going on, although i cannot think of any reason that i would have only encountered this problem in the last week. I have been driving this truck for months.

 

I will bring this up with the shop if shifting slowly does not solve the problem.