SQL Server Extended Event - How to reduce the fields of the event "sql_statement_completed"?
I'm going to say you are getting all the extra fields because you picked a template when you built your event session (or used the wizard). If you only want certain fields then go uncheck what you don't want. However, there will be some event level info that will always be there, what is shown under the "Event Fields" for each event are their by default and cannot be removed.

Default event for "sql_statement_completed" only captures this, after I checked the global field for client application name: