What causes display issues with Apple CarPlay on my Ford Escape 2018?

I have an installer putting in 9" Apple CarPlay Radio GPS Navi Wifi W/CAM Android 13 For Ford Escape 2013-2019 and it is the correct unit for my car. It is supposed to work. He says everything works until he puts the car in reverse and then the screen has a squished picture, then a black line then that repeats 2 times for a total of 3 squished pictures and black lines. Any ideas on how to fix this or do you think it is a problem with the unit.

Thanks in advance

Mleader

[Edited by Moderator]