Think of unsubscribing a user as moving them to a 'Do not contact further' list. When you click 'unsubscribe' on a user, it will hide them from the review manager workflow tab but they will stay in your customers tab so if you ever want to add them back you can. This helps remove the chance that someone on your team accidentally contacts a user that explicitly did not want to be contacted.
Sample use cases for unsubscribing customers in the review manager:
If you accidentally upload a client you don't want to reach out to with a review campaign
If a client is in an active campaign but you want to stop the campaign
If a client has finished a campaign and you don't want anyone on the team to 'followup' or reach out again
If I accidentally archive/unsubscribe a review in the Review Manager, how can I undo this to have them reappear?
When you unsubscribe a user in the review manager it keeps them in the 'clients' tab so you can view their history or re-subscribe them but it moves them out of the 'review manager' flow so your team knows not to reach out to them.
To make a user reappear back in the review manager, simply filter or search for the user in the clients tab > click 'view detail' to open their history > then click the 'resubscribe' button (shown here).