I have a 2020 Trail Boss with the exact same issue. My truck was purchased in April 2020 and now has 24k miles on it. The truck was quiet as can be until about the 20,000 mile mark. Oil has been changed and tires rotated every time. Alignment has been done every oil change also to make sure I get the most life out of my tires. I am not getting vibration but the road noise between 30-60 mph is unbearable.
Firestone says there is an issue with the suspension and it is a warranty issue. GM says the alignment and suspension have no issues, but the tires are feathered severely and recommends replacing the tires.
I did not choose the tires, GM did. Why would the consumer have to try to fight with Good Year for tires that were purchased by GM for this truck? If the alignment and suspension are good then why would these tires feather and have issues if everything else is good? And as the consumer of a $50,000 + truck we are left holding the bag for the cost of new tires. I can guarantee you they wont be replaced with Good Year tires if I have to pay for them.