On the Fenix 7 series, and probably many other series, when a notification comes in from the phone while the stopwatch is running, the entire screen gets covered by that notification. However, stopwatches are often used to measure seconds, or even milliseconds. Everything gets messed up by an interrupting notification just when you're about to measure the duration of something important. By the time you press the back button, exit the notification, everything you were measuring is gone. Even if there wasn't a solution for back button, I might be okay with the notification taking up half the screen, as long as I could still see the seconds at that moment. This is an incredible UX flaw, especially for a brand like Garmin that produces athlete-focused products.