How to Block Names From Completing Your Form – First Last and First Middle Last format

/**

 * Prevent certain names from the other formats for the Name form field.

 *

 * @link https://wpforms.com/developers/how-to-block-names-from-completing-your-form/

 */

function wpf_dev_block_name_validation( $field_id, $field_submit, $form_data ) {

    // Bail early if form ID is not 1000 and field ID is not 10

    if ( absint( $form_data[ 'id' ] ) !== 1000 || absint( $field_id ) !== 10 ) {

        return;

    }

    // Form builder Name format is set to First Last

    $submitted_name = $field_submit[ 'first' ] .' ' .$field_submit[ 'last' ];

    // Create your list of names to be blocked separated by commas

    $blocked_names = array(

        'John Doe', 

        'Jane Doe',

        'Jack Doe'

    );

    foreach( $blocked_names as $name ) {

        if( preg_match( '/\b' .$name. '\b/i',$submitted_name) ) {

            wpforms()->process->errors[ $form_data[ 'id' ] ][ 'header' ] = esc_html__( 'Can\'t submit form. Please try again later.', 'wpforms' );

            return;

        }

    }

}

add_action( 'wpforms_process_validate_name', 'wpf_dev_block_name_validation', 10, 3 );