function THEME_NAME_theme_suggestions_block_alter(array &$suggestions, array $variables) {
  $current_path = Drupal::service('path.current')->getPath();
  $result = Drupal::service('path.alias_manager')->getAliasByPath($current_path);

  $path_alias = trim($result, '/');
  $path_alias = str_replace('/', '-', $path_alias);
  $path_alias = str_replace('-', '_', $path_alias);
  $id = $variables['id'];

  $suggestions[] = 'block__path_alias__'.$path_alias;
  $suggestions[] = 'block__' . $id . '__path_alias__'.$path_alias;
}