What are the content list markups ?

Content list markups can be enable in component settings
... and can override in category settings and in content type settings

-- currently there are 3 type of content list markups:
a. Access Level Markups (your case: red lock=no access):
 - free-access,
 - no-access,
 - need-access levels,
 - obtained-access levels

b. featured categories markups

c. normal categories markups (you rarely need to enable this markup)

Regards