But in case anyone’s reads this thread looking for an answer, here are a few issues I found on the forum that cause a noise in the rear
1.) the headrests, pull them out and spread the prongs out just a little to snug up the fit
2.) Make sure your tire jack is secure
3.) The seat belt covers in the c pillars are loose and can rattle
4.) And if your hearing a pop once in a while, it’s your spoiler on the outside of your car
5.) lastly, check the chain linkage for the rear slider power wire. It presses up against the glass