The page sc_home is service portal look different than an OOB instance or developer instance in Kingston.
Kingston , London
This is happening because of the plugin which is not installed on the instance but is activated on the developer instance or OOB zbooted instance.
Plugin Name : Service Portal - Service Catalog v2
ID : com.glideapp.servicecatalog.portal
In Kingston, we introduced the "Service Portal - Service Catalog v2" plugin which changed the way "sc_home" looks and behaves. Any portal using the "sc_home" page on a Kingston instance will look the same way.
For more information on how to activate a plugin go through below documentation.