Graph API - Update Event

Question

Hi Team,

We have developed a web app that provides the function for users to subscribe to specific Group/Teams events.

We achieved the goal by leveraging the Update Event endpoint to add the current user to the attendees object in the Event payload. After the request been successfully made, the event will be synchronized to user's calendar.

But there are scenarios that the users will occasionally receive notifications from the outlook while the update action does not send this kind of notification by default:

Currently we have no idea on how does the request trigger this kind of notifications, please advise.

Thanks.