Output ACF Repeater field values as a comma-separated string in Listing Builder items

<?php
add_filter( 'facetwp_builder_item_value', function( $value, $item ) {

  if ( 'el-isuok7' == $item['settings']['name'] ) { // Replace 'el-isuok7' with the'Unique name' of your Listing Builder repeater item

    $fieldvalues = get_field( 'automerkit' ); // Replace 'automerkit' with the name of your Repeater field
    if( $fieldvalues ) {
      $output = array_map(function($arr) {
        return implode(', ', $arr);
      }, array_map('array_values', $fieldvalues));
      $value = implode(', ', $output);
   }

  }
  return $value;

}, 10, 2 );