This update has been retired. Salesforce won’t enable this update in all Salesforce orgs. Instead, you can choose when to restrict who can view record names in lookup fields with an opt-in setting on the Sharing Settings page.
When: This update has been retired and no longer appears on the Release Updates page in Setup.
How: To enable the opt-in setting, from Setup, in the Quick Find box, enter Sharing Settings, and then select Sharing Settings. Click Edit in the Organization-Wide Defaults area, then select Require permission to view record names in lookup fields.