Actually, it is the suggested keywords that handle from the Joomla smart search.

For example, when a new user signs up on the site, the Joomla will index this user's full name in the database but we can't control what keywords Joomla stores in the database.

From what I checked, the search is no problem, the system still can manage to find out the user if you only key in the keyword that you described above.

To turn off this "suggestion keyword", you can disable this setting from the backend > Easysocial > setting > general > Enable Keywords Suggestion In Toolbar Search