Exactly. The trailer works fine on a different tow vehicle, and my truck works fine on a different trailer.

 

Pull both connectors under the rear bumper, clean, and apply electrical grease. Unscrew the ground connector there, clean it, and tighten the scew. Then clean out the 7-pin connector for the trailer. Hook up and try again. If nothing changes, get some small wire, cram in the ground and brake pin slots in the trailer connector, and run to the cab so you can connect a multimeter so you can see the voltage when you engage the brakes. You'll either fix the issue, or be able to report to the dealership that the truck is not providing full voltage to the trailer.

Squeezing the lever fully will send a full 12V to the trailer brakes. Using the brake pedal will not unless you depress it fully.

 

The place I bought my trailer said they tested my truck and it did provide 12 V.

My dad also bought a 2020 F150, so I decided to hook up the trailer to his truck.... wouldn't lock the brakes.

Thank you for the good info.