General Motors complaint: GMC Sierra pickup shuddering at all speeds caused by bad transmission fluid installed at factory

My 2018 GMC Sierra 1500 Z71 4×4 began shaking or shuddering as though tire was out of balance. Checked all wheels and all balanced . But problem continued and got worse. I took truck to Dealer in Uvalde, Texas. Dealer said it is known problem for years caused by the wrong transmission fluid installed by GMC at the factory. Dealer said it could be fixed by fluid change and I would have to pay for GMC mistake because the solution is a maintenance item. I was charged $501.55 for fluid and labor! I am concerned that this GMC error may have caused some permanent damage to the transmission that will result in a huge expense for premature replacement. I see that many people have reported this problem with various GM vehicles over the years. I also see that various dealers have done the fluid exchange at no charge to the customer. I believe that GM is cheating their customers by not notifying about the extensive problem they alone have caused and not paying for repairs. I want GM to pay for my repairs and any future transmission problems.