Took my 2019 silverado high country in yesterday for the same squeaky noise. They called me today that they couldnt hear the noise. Went for my truck and drove it around so it could heat up and the noise would pop up. Took it back and the manager got on with me. He heard the noise and i told him the bulletin code and everything. Put the truck in auto and the noise went away. He called the gm people and they told him there wasnt a fix and that they couldnt change anything on the truck until they got the solution. To keep on checking up with them to see if they have a fix already. They know the problem is going on and havent found a fix.