Map Marker content for multiple locations per post (with ACF repeater fields)

 * Set marker content specific to the ACF repeater locaton.
 * Change 'locations_multi' to the name of the ACF repeater field.
 * Change 'store' to the name of the Google Map field within the repeater field.
 * Add other or different code as needed to $args['content']. This overwrites anything in the 'Marker content' setting.
 * For more info and an example on how to use other custom fields within the repeater field, see:

add_filter( 'facetwp_map_marker_args', function( $args, $post_id ){

    $latitude = $args['position']['lat'];
    $locations = get_field( 'locations_multi', $post_id );

    foreach ( $locations AS $location ) {
        if ( (string)$location['store']['lat'] == (string)$latitude ) {
            $args['content'] = $location['store']['address']; // Retrieves Google address from the Google Map field.
            // Or:
            // $args['content'] = $location['other_field']; // Retrieves value from another custom field in the repeater

    return $args;

}, 10, 2 );