Hi @CHATILLON Laurent ,
I tried to create few events and delete/cancel them using graph. After checking the Attendees deleted folder, I can see all the deleted events. And I was also able to get the deleted events using Graph API.
Please note that the deleted events will be stored in Attendees deleted folder only and not organizer.
I would recommend you raise a support case with Microsoft Graph, a Support Engineer will be able to assist you better. You can raise support ticket from
http://aad.portal.azure.com/ or https://admin.microsoft.com/#/support/requests.
Hope this helps.
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