It turned out to be a bug in Firebase Cloud Messaging. I've turned off method swizzling and it worked. Look up on the internet "Method swizzling in Firebase Cloud Messaging" on how to turn it off

I'm experiencing the same issue, but it also happens on a real iPhone. Not getting silent notification when it's a SwiftUI app. When I remove @main from struct App and put @main at AppDelegate, everything works like a charm. I think it's a bug in SwiftUI

Ended up by performing authentication in the default external browser