Gravity Forms Antispam

gravityforms-antispam.php

<?php
 /**
 * Gravity Forms Antispam
 * Check if field has a predefined value
 * https://docs.gravityforms.com/gform_field_validation/#1-number-field-validation
 */

function gf_antispam( $result, $value, $form, $field ) {
 
    if ( $result['is_valid'] && intval( $value ) !== 9 ) {
        $result['is_valid'] = false;
        $result['message'] = 'Please enter correct value';
    }
    return $result;
}

// Form ID 2 , Field ID 8
add_filter( 'gform_field_validation_2_8', 'gf_antispam', 10, 4 );

https://pabstwp.de/blog/gravity-forms-antispam-massnahmen-fuer-formulare/