Change order of breadcrumbs elements in hook hook_system_breadcrumb_alter
Create a new breadcrumb instance:

$links = $breadcrumb-&gt;getLinks();
// change order of $links
$cacheability = \Drupal\Core\Cache\CacheableMetadata::createFromObject($breadcrumb);
$breadcrumb = new \Drupal\Core\Breadcrumb\Breadcrumb();
$breadcrumb-&gt;setLinks($links);
$breadcrumb-&gt;addCacheableDependency($cacheability);