Transmission Shudder problems of the 2018 GMC Canyon

I just purchased a 2018 GMC Canyon used with 8,000 miles on it. Drove it 500 miles and now I have a 8 speed transmission and now it shudders. Now I'm reading alot of people are having issues with it. Am I in the lawsuit with gm in there defective transmissions? it shudders at 55-60 mph drove me nuts on the highway.

When moving on the highway the vehicles� transmission starts to shudder. This usually happens when I am going up a slight incline and my engine is around 1400 rpms. I have taken the truck to the dealership multiple times over this issue. They have replaced the transmission fluid twice and the next appointment is next week on October 31st. The dealership told me that more than likely they will have to flush the transmission fluid again because gm is not letting them do much more with this issue. The truck also has a hard time shifting when it is first started until it gets warmed up. Also there are times I feel like I have been rear ended when I am slowing down and it is down shifting. I have noticed that if I keep the truck at a fairly higher rpm that it does not shudder as bad and doesn't feel as dangerous to drive. My vehicle has 27,000 miles on it and has been in the shop countless times since I purchased it in 2018. I don't even like driving it because I feel that it is a safety concern and is endangering myself and others.