Leftover 2023 Sierra AT4x with a 10 speed transmission. When I unlock the doors in the morning, there is a high pitched whine from the transmission fluid reservoir. This is not the fuel pump. At times, I can get the whine to repeat just by locking and unlocking the doors. It sounds like a pump priming, I can both hear and feel the vibration of fluid moving, but I believe the transmission oil pump is gear driven? The truck is in the shop for this issue, but I am hoping someone might have an idea for what is causing it. I cannot find anything about the transmission priming prior to starting. Video attached:

I should add, this noise is present before the truck is running. I walk up, hit unlock, and hear this whine.

Something in that unlock request is bleeding into that pump circuit somehow. Interested as to what they find.

I'm being told it'* the parking brake setting itself. I don't really agree with that...doesn't make any logical sense. 4 techs, including a master tech, have looked at it and that'* the answer