How to disable notifications in game mode under Windows 10
Disable game notifications from Windows 10 Game This Bar
opens Game bar settings in Windows 10. In the Settings window, click Notifications on the left to view all Game bar alert options.
When a notification appears, swipe up on it and tap the Settings icon.
You go directly to the notification settings.
Disable Game Mode here to enable Game Mode.
(You can quickly open the Preferences window by pressing Windows+i.) In the Automatic Rules section, click the name of the automatic rule. For example, to turn off the Focus Assist notifications that appear when you’re playing Game A, tap When I’m Playing Game A.