Thank you for your patience.
Based on the information provided, the issue appears to be related to the Azure DevOps Graph identity continuing to reference the historical guest identity after the guest account was recreated in Microsoft Entra ID.
Recommended resolution:
Instead of deleting and recreating the guest user when only the email address changes, Microsoft recommends using Reset Redemption Status in Microsoft Entra ID.
This updates the guest's sign-in email while preserving the existing Object ID, allowing Azure DevOps to continue recognizing the same identity without creating a new Graph mapping.
If the guest has already been deleted and recreated, Azure DevOps may continue to reference the previous identity mapping. Currently, there is no customer-facing option to manually reset or remove the Azure DevOps Graph identity cache or descriptor mapping. Identity information is synchronized from Microsoft Entra ID and will refresh automatically over time.
As we have not received any further updates, If the issue persists after the identity synchronization completes, or if you have additional findings, please feel free to share the response. We'll be happy to continue assisting you.
If the above steps did not help resolve your issue, please feel free to share the requested details in a private message so we can proceed with further troubleshooting over a Teams call. I am happy to connect with you on Teams to investigate and resolve the issue.
Thank you for working with Microsoft Support