What is this sound?

Peterbilt 579 2019 Weird sound when accelerating into 11th, 12th and 13th gear. Weird sound when decelerating. Weird sound stops when Jake Brake is applied. Weird sound isn’t present when accelerating until it hits about 70 mph in 13th gear.

Engine light has been diagnosed as “humidity sensor” Transmission and differential have clean fluids and are full.

Anyone have a similar experience in their Peterbilt? How did you resolve?