facetwp add lables to google map icons

custom-hooks.php

<?php
/** add map facet icon labels **/
add_filter( 'facetwp_map_marker_args', function( $args, $post_id ) {
    $args['label'] = esc_html( get_the_title( $post_id) );
    return $args;
}, 10, 2 );