Hello, I also have a rattling and creaking noise in my Y (MiC 2022).
Unscrewing the spacer bolts minimizes it, but the lock is under extreme tension.
Maybe with some felt or foam underneath?
I suspect that it is at the top of the tailgate, where the black trim (near the brake light) meets the seal on the roof.
I've been looking for about 2 months now. I've already insulated and lined everything in the trunk at the bottom and sides. Unfortunately the noise is still there.