Debugging your render cacheable metadata in Drupal
One of Drupal's greatest features, and often mysterious underworking to many site builders and developers, are its caching layers especially render caching. We have all been there before: we have no idea why it's not quite working, so we press "Cache rebuild" (or more infamously, "Flush all caches" of the pre-Drupal 8 eras), and like magic, things are displaying properly.