What is causing the squealing or whining sound only in reverse on a 2010 santa fe?

The squealing or whining sound when reversing in a 2010 Santa Fe could be due to several factors, such as worn brake pads or shoes that are more pronounced in reverse. It could also be caused by issues with the transmission or differential, particularly if the noise is accompanied by other symptoms. Additionally, a loose or damaged serpentine belt may slip when the vehicle is in reverse. It's advisable to have a professional mechanic inspect the vehicle to accurately diagnose and resolve the issue.