Why are Apple Watch's local notifications delayed?

I created an app for Apple Watch with a companion app for iPhone. These two apps test the local notifications on both devices.

But since I updated to iOS 13.1.2 and WatchOS 6.0.1, the local notifications on Apple are delayed: when I press the button on the watch that creates the notification and I exit the app, it doesn't take 5 seconds to display the notification but about 20 seconds... when I change the code to 3 seconds it takes 16 secs to display.

Is this a new feature on Apple Watch or a bug? Because on iPhone it works without any delay.

Thank you in advance :)

    // Configure the notification's payload.
    let content = UNMutableNotificationContent()
    content.title = NSString.localizedUserNotificationString(forKey: "Hello!", arguments: nil)
    content.body = NSString.localizedUserNotificationString(forKey: "Hello_message_body", arguments: nil)
    content.sound = UNNotificationSound.default

    // Deliver the notification in five seconds.
    let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)
    let request = UNNotificationRequest(identifier: "FiveSecond", content: content, trigger: trigger) // Schedule the notification.
    let center = UNUserNotificationCenter.current()
    center.add(request) { (error : Error?) in
         if let theError = error {
             // Handle any errors
         }
    }

EDIT:

I also noticed this strange behavior: when I create a notification on iPhone, pressing the button and then put the phone on stand by so the notification gets delivered to Apple Watch, the notifications gets displayed correctly after 5 seconds on the watch!

I've just updated my Apple Watch to WatchOS 6.1 and yes... they fixed the bug!!! Now the notifications created locally get triggered on time :)