What would cause a squealing sound when letting off gas pedal?

A squealing sound when letting off the gas pedal can be caused by several issues, including worn or loose serpentine belts that may slip under load. It could also indicate problems with the brakes, such as worn brake pads that are making contact with the rotor. Additionally, issues with the engine's accessories, like a failing alternator or Power Steering pump, could contribute to the noise. Identifying the source typically requires a thorough inspection of the vehicle's components.