Почему после отправки формы в Symfony 4 isPasswordValid() работает иначе, чем до отправки?

public function changePassword(Request $request, UserPasswordEncoderInterface $encoder)
    {

        $plainPassword = 'Test1234';

        # Working -- echo 1
        if ($encoder->isPasswordValid( $this->getUser(), $plainPassword)) {
            echo '1 Current password true'; # Password in data base: Test1234
        } else {
            echo '2 Current password wrong';
        }


        $form = $this->createForm(ChangePasswordType::class, $this->getUser());
        $form->handleRequest($request);

        if ($form->isSubmitted()) {

            # When submit form -- not working -- echo 2
            if ($encoder->isPasswordValid( $this->getUser(), $plainPassword)) {
                echo '1 Current password true';
            } else {
                echo '2 Current password wrong';
            }
            die;