Is 'developer' tab in Reports now a deprecated feature?
To view developer tab for the report the user will need 'CiviReport: view report sql' permission. This is new permission added in recent version of CiviCRM for broader access control.

You can set permission by navigating to CiviCRM >> Administer >> Users and Permissions >> Permissions (Access Control) >> WordPress Access Control

HTH

Pradeep