CSV export all core fields ?

Hello,
When I export items with CSV, the CSV file contains all core fields despite I set these core fields to "No" (fields parameters : "Include in CSV export" >>> No).
Is it a bug ?

Thank for your answer.

Hello in front or in back ?

I test it in frontend.

strange can you do a an export in backend to compare it ?

I don't know how to export in backend ?
I know how to import (in "content import"), but I don't find the export function.
In "Apps import / export", the only thing I can export is xml files with elements parameters. But not the content.
Could you tell please me where I can find backend export in csv file ?

in global configuration you can allow exporting in backend
csv export > backend