I would contact the Ford GT Concierge .
Have your serial number ready.
From what you describe it is the module.
The new modules revised the sealing design that prevented moisture from entering
and corroding.
Several vehicles had modules replaced with new design…(mine was one of them)
Back then it was under warranty.
Not surprised they are expensive.
Andy (ajb)
Hello Bornn66, I just finished up a 2021 Ford GT with the left side Tail lamp not working and had to replace the tail lamp module. In the early cars I would see a lot of them but have not seen any on the later model years until i got this 2021. I know the cost is high and took me 2 months to get the part. Since it's an led light I could not find any other way to fix it. Wish I could have been more help.