We previously announced the SIEM REST API would be deprecated on 4/1/2022. We've listened to customer feedback and the API deprecation has been postponed for now, more details expected in Q3, 2022. ...
Updated Mar 29, 2022
Version 5.0
Blog Post
tennisr7 since that Azure AD app WindowsDefenderATPSiemConnector references the Azure AD Graph API as well which is also being deprecated, it's best to create a new app and add any additional permissions there.
Create an app to access Microsoft Defender for Endpoint without a user | Microsoft Docs
AAD Graph API deprecation FAQ: Azure AD Graph to Microsoft Graph migration FAQ - Microsoft Graph | Microsoft Docs
** Please note the Azure AD Graph API is different than the Microsoft Graph (AKA Intelligent Security Graph (ISG)). The Microsoft Graph is NOT being deprecated.**