payment_term.id, creates a tuple wich works if payment_term.id is set in case payment_term.id is False this creates the tuple (False,) which is then converted by the Odoo ORM to a account.payment.term(False, ) record set, which in term may cause weird behaviour as this value does not eval to false in cases like `if self.payment_term_id:` Closes odoo/odoo#28397