Yelping noise while towing a trailer

[Truman]

I have a 2025 F-150 Power boost. When I am towing my camper I hear a yelping noise that sound like its coming from under the hood. I am noticing it at around 2800 rpms and not applying throttle and I am somewhat coasting. I was thinking it was some type of wind noise from the camper but I can make it stop if i apply slight throttle and going above the 2800 RPM. It only does this while I am towing my camper. The best descripting I can give as to the sound is it sounds like a police yelp siren, but not quite as loud. Anyone have any ideas ?

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[WoodBarn Mark]

Mine makes a kind of whistle while pulling the trailer. It only happens when i let off the gas when going uphill. I believe that higher elevation also is a factor. I think it has to be the turbos. I don't know what else it would be. It's kind of a 3 part whistle... high low high... really fast, and pretty quiet.