Ended up by performing authentication in the default external browser

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

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