Hi,@Imteyaz Ahmad
Thanks for posting your question in the Microsoft Q&A forum.
Based on your description, I ran the relevant tests and the results were the same as yours.
The Name parameter associated with a recipient within a tenant in Exchange Online should be unique. However, while we sync objects from Azure Active Directory to Exchange Online, the way Name parameter (system metadata) is being computed in the backend currently led to some system conflicts impacting reliability. We realized that the current method is not the best way to compute this parameter. Hence, we want to move away from the status quo to a more robust way of generating the Name parameter which is through ExternalDirectoryObjectId (EDOID) that ensures uniqueness in the system. All the long-term reliability enhancements in the backend would be done in line with this change.
You can refer to this link for details:https://techcommunity.microsoft.com/t5/exchange-team-blog/change-in-naming-convention-of-user-s-name-parameter/ba-p/3284733?WT.mc_id=M365-MVP-9501
If my answer is helpful to you, please mark it as the answer so that other users can refer to it. Thank you for your support and understanding.