Ipad iOS 14: icon badge flickering

Question

I've found this strange behavior on ipad running ipados 14 (I've in both simulator and physical device installed 14.5, with 14.5.1 in the real one).

I need to show an icon badge with a number based on work made within the app, so there is no external push notification service involved in this.

I've set up a ViewModel that keep track of the number to show in the notification badge:

import Combine
import Foundation

class CounterViewModel: ObservableObject {
    @Published private(set) var notificationCount = 42

    func up() {
        self.notificationCount += 1
    }

    func down() {
        self.notificationCount -= 1
    }
}

To publish this number on the notification badge on the app icon I'm using the .onAppear method of the contentView

struct ContentView: View {
    @EnvironmentObject var counterViewModel: CounterViewModel
    @State private var counterCancellable: AnyCancellable?

    var body: some View {
        Text("Hello World!")
        .onAppear {
            UNUserNotificationCenter.current().requestAuthorization(options: .badge) { _, error in
                if error == nil {
                    self.counterCancellable = self.counterViewModel.$notificationCount.sink { count in
                        DispatchQueue.main.async {
                            UIApplication.shared.applicationIconBadgeNumber = count
                        }
                    }
                }
            }
        }
    }
}

Finally, the EnvironmentObject is set up on the app

struct IBreviaryApp: App {
    @ObservedObject private var counterViewModel = CounterViewModel()

    var body: some Scene {
        WindowGroup {
            ContentView()       
                .environmentObject(self.counterViewModel)               
        }
    }
}

so I can share on all the view involved in this count mechanism.

The problem: on the first run of the app, and only on the first one, after accepting the alert about authorising the notifications, when the app is put on background the badge within the icon is shown, but suddenly disappear. In the dock does not even show. If I click the app (both on dock or on the "desktop") the badge appear in the animation that open the app. If I scroll between the pages of installed applications and return to the one where my app is installed, the badge now is fixed. If I open another app, so the dock show this new app in the recent used app list, the badge appear here also (and stays this time).

Restarting the ipad or reinstalling the app fixes the problem, but itself remain for the first time you run the app.

EDIT: repo here: https://github.com/artecoop/badgebug To actually make the problem arise, I needed to change the count number from another function.

EDIT 2: Here's a video: https://youtu.be/tPWYRm5xFXI As you may already see on the repo, to mimic another interaction, I've added a 5 second delay and then set 42 in the counter.