Squeaking noise when cold.

Hey guys, new to the forums.
I’ve been trying to find some information on this but everything I look up either leads me to suspension squeaks or other noises but nobody seems to have the same issue as me. This started happening when the temperatures dropped below 50ish. Every time I start my car and start driving I hear a squeaking noise coming from the rear end of the car. It’s only when coasting or under very light load and it goes away after a couple miles. It seems to change with speed and if I immediately get the car up to highway speeds it goes away faster and it won’t come back until the next time I drive the car while it’s stone cold. It’s not affected by bumps in the road and it’s just a consistent high pitched squeak that gets quieter as the diff and transmission warm up.
My car is a 2012 GT, 6 speed with about 120k.

Rear brakes low? Possible wear indicator noise?

Chock the front wheels so the car can't roll forwards or backwards, release the handbrake, jack the rear of the car up with both rear wheels in the air, ask a buddy to spin each wheel manually until the noise is replicated, and listen closely to localize it.