Limited-access user permission lock down mode feature
This feature Limits the access permission for anonymous users on application pages.
This page will shows all content of the site, and lock down mode can be turn on or off.
Lockdown mode is available as a site Collection Feature! And Site collection administrator can control it using the UI
Site settings > Under Site Collection Administration section > Site Collection Features > Active/Deactive
Limited-access user permission lockdown mode feature depends on (SharePoint Server Publishing Infrastructure) Feature and it’s important for SharePoint internet websites.
Advantages of Limited-access user permission lockdown mode feature:
Site collection Admin can control without need to use Power shell or get Farm Admin permission.
Secure publishing sites application pages from anonymously access.