old_contents: from odoo import api, models
  
  
  class AccountMove(models.Model):
      _inherit = "account.move"
  
      @api.onchange("partner_id")
      def _onchange_partner_id(self):
          res = super(AccountMove, self)._onchange_partner_id()
          self._onchange_partner_shipping_id()
          return res
  
      @api.onchange("partner_shipping_id")
      def _onchange_partner_shipping_id(self):
          res = super(AccountMove, self)._onchange_partner_shipping_id()
          self.tax_on_shipping_address = bool(self.partner_shipping_id)
          self.is_add_validate = bool(self.partner_shipping_id.validation_method)
          return res
  
new_contents: from odoo import api, models
  
  
  class AccountMove(models.Model):
      _inherit = "account.move"
  
      @api.onchange("partner_id")
      def _onchange_partner_id(self):
          res = super(AccountMove, self)._onchange_partner_id()
          self._onchange_partner_shipping_id()
          return res
  
      @api.onchange("partner_shipping_id")
      def _onchange_partner_shipping_id(self):
          res = super(AccountMove, self)._onchange_partner_shipping_id()
          self.tax_on_shipping_address = bool(self.partner_shipping_id)
          return res
  
subject: Remove 'is_add_validate' field