@Gokul Unfortunately, there isn't a dedicated Microsoft dashboard specifically for the Windows Notification Service (WNS) health status. The Office Portal and Azure Portal do not include WNS service health information.
Regarding incident history reports, Microsoft does not publish a specific incident history report for WNS impacts. However, service health information, including incidents and maintenance, is generally available through the Microsoft 365 admin center. You can check the Service health section there for any related updates or notifications.
Thank you for your understanding on this matter.