path.php

<?php

  public function getSOMPath($url, $path, $langcode) {
    // Load the site's parent link configuration.
    /** @var \Drupal\Core\Config\ImmutableConfig $site_config */
    $site_config = \Drupal::config('som_breadcrumb.settings');
    $data = $site_config->get('site.active_trail');

    // Load the site homepage alias
    $site_config = \Drupal::config('system.site');
    $site_homepage_path = $site_config->get('page.front');

    // Get the current alias from the path
    $som_path = !($url->getOption('alias')) ? \Drupal::service('path.alias_manager')->getAliasByPath($path, $langcode) : $path;
    
    // Get the site homepage alias from the path
    $site_homepage_alias = !($url->getOption('alias')) ? \Drupal::service('path.alias_manager')->getAliasByPath($site_homepage_path, $langcode) : $site_homepage_path;

    // Explode the current alias into component parts
    $som_path_array = explode('/', $som_path);
    
    // If the first part of the current alias equals the site homepage alias, remove it
    if ($som_path_array[0] == $site_homepage_alias) {
      array_shift($som_path_array);
      $som_path = implode("/", $som_path_array);
    }
    
    return $som_path;
}