Vibration at 70 plus MPH

I recently purchased a 2020 Cherokee Limited. I immediately noticed a
vibration above 70 mph. I took it back to the dealer, they replaced the front
tires (Continental Pro Contact.) It seems a little better. I then took it to
another dealer. They basically dismissed the concern.  They checked the
balance of the rear tires and said they were good. I still feel the vibration
basically through the gas pedal and the floor. It does not increase or
decrease with the engine RPM (the 3.2 L). I traded in a 2015 Cherokee
Trailhawk with 82,000 miles, and never felt this sensation at higher speeds.
Not sure what to do now, any suggestions?