External entities with a UUID as ID or any ID containing characters not accepted by hook_theme_suggestions_HOOK() generate unusable template name suggestions. The template name suggestion doesn't work, and could be hard to figure out why. Twig debugging makes notice of this.
it looks like this when twig debugging is enabled:
<!---
INVALID FILE NAME SUGGESTIONS:
See https://api.drupal.org/api/drupal/core!lib!Drupal!Core!Render!theme.api.php/function/hook_theme_suggestions_alter
external_entity__b719a2fa-e401-4c97-b0b2-c33cb2a97693__full
external_entity__b719a2fa-e401-4c97-b0b2-c33cb2a97693
--->
sanitize the ID while generating theme suggestions.
Needs review
Code