AAid gets unlinked while changing an email from Managed to UnManaged vis SCIM

Issue Summary

Email change from Managed to Unmanaged is prohibited in Atlassian Cloud.
However, when this change is triggered via SCIM, the AAid- SCIM link gets broken.

This is reproducible on Data Center: (yes) / (no)

Steps to Reproduce

1. Push an update for an account to change the email from Managed to Unmanaged via SCIM
2. The email gets updated on IDEA however the AAid of the old user is removed from SCIM

Expected Results

The update fails on SCIM and an error is shown

Actual Results

IDP-Atlassian SCIM link breaks for the user.
Org Admins get confused so as to what exactly happened.

1. We see the following error in the Provisioning logs:

Email update to unmanaged user with ID ********, primary email user@domain.com, unlinked any associated Atlassian account.

Workaround

Relink the AAid with SCIM by the help of maintenance API however, even this will end up with the user having 2 Atlassian Accounts