Groups writeback enables customers to leverage cloud groups for their hybrid needs. If you use the Microsoft 365 Groups feature, then you can have these groups represented in your on-premises Active Directory. This option is only available if you have Exchange present in your on-premises Active Directory.

It takes your M365 Cloud groups and recreates them on-premises, in a configurable target OU.

Enabling or disabling this feature is fairly easy, and is wonderfully explained here. However, when migrating towards another server or version of AAD Connect, finding out in what OU the groups are / have to be stored is not that transparent.

Fortunately, there is a way! Using the below PowerShell line, the OU is displayed:

Get-ADSyncGlobalSettings |Select -ExpandProperty Parameters |Where {$_.Name -eq "Microsoft.GroupWriteBack.Container"}

If Group WriteBack is not enabled, the results of the above command will be empty. When it is enabled, it will show the OU in the value attribute: