tval5

I recently brought my 2019 Colorado ZR2 to my local Chevy dealer and i was told there was an "internal failure" and the transmission needs to be replaced. The truck has 79,200 miles. Here is the issue i am having when i am braking while coming to a stop i get a bucking almost as if the truck is going to stall. It will buck/shudder ? once or twice sometimes slightly harder than others. And this only happens in drive it does not happen in reverse. The truck does not stall. If i put the truck in neutral after coming to a stop the engine will rev to 5500-6000 RPMS then slowly come back down to under 1000RPMS. Has anyone else had this issue and if so how did you fix the problem ?