verify-valid-email.php

<?php

add_filter('forminator_custom_form_submit_errors', 'my_custom_form_validation', 10, 3);

function my_custom_form_validation($submit_errors, $form_id, $field_data_array) {

  // Skip if is not the correct form
  if( (int) $form_id !== 49 ){
    return;
   }

    $fields = [];
    $fields[] = $_POST['email-1'];
    $fields[] = $_POST['email-2'];


      // Check if both emails are the same
      if (count(array_unique($fields)) !== 1) {
        // Custom error
        $submit_errors[][ 'email-2'] = __( 'Emails does not match' );
      }

  // Always return $submit_errors
  return $submit_errors;

}

Hi @patrickfreitasdev , Thanks for that info.
It seems to be that the current wording isn't ideal. It makes it sound like there is an error with the form itself.
I suspect it would be clearer and less ambiguous if it stated something like, "Submitted form data is invalid. Check for error messages within the form". Something along those lines.

I'll post a support ticket.