Pulsing Air Pressure Sound In Reverse

[mattc262]

I just purchased a used 2021 Expedition Limited yesterday. It has 58k miles. I have an extended warranty so I’ll be covered but wanted to ask if my issue is common. When I put the vehicle in reverse (only reverse) it makes a pulsing air pressure/hissing sound every second that stays the same whether I’m stationary or moving. Anyone experience this and know what it might be? I’ll try to get my video attached, but it’s currently not letting me I think due to file size.