Symfony validate form with mapped false form fields

I've got a form with extra fields added with the option mapped to false. But when I try to validate my form, it won't pass indicating "this value is not valid" above these specific form fields. Isn't this option supposed to bypass validation?

These form fields are only useful for populate other fields and I don't need to save or even check them.

The only solution I found is to remove all extra fields with js on a submit button click.