Issue with domain cutover: Error: "Time out waiting for on-prem changes made by DirSync to sync to the cloud" (4332002)

Stuck on errors related to removing source emails

We see the following error: "Time out waiting for on-prem changes made by DirSync to sync to the cloud for domain.com, timeout of 4:00 hours exceeded.

Directory Sync workflow to remove domain has finished with errors

Failed to remove source addresses (On-Prem) for domain.com.com Directory Sync workflow to remove domain has finished with errors.

There are any number of reasons this may fail. The files may be locked or a part of groups or some other weird environmental oddity which we do not have visibility into to.
For example someone may have run the hybrid wizard and then changed their mind. There could be environmental issues which the product cannot ascertain the cause and provide guidance to find root cause like missing SIP addresses attached to unlicensed accounts within the environment.

Our product fails to proceed due to some issue in the environment, the accounts should be checked to determine root cause. There may be a problem with Azure AD Sync.

Review the environment with the appropriate administrators.

Confirm the following is enabled; MSOL DirSync feature SynchronizeUpnForManagedUsers for the changes to reflect in AAD.
If the source is hybrid, check the Entra/Azure AD Connect logs for any outstanding issues.

Once this is resolve the cutover should be able to proceed to the next step.