Cannot access uploaded file when in private://

Relevant aspects:

FileUrlItem::schema() -> the 'foreign keys' are removed a this affects file_field_find_file_reference_column()

In this code block, the if condition will be always FALSE with file_url fields:

              if ($file->id() == $item->{$field_column}) {
                $references[$file->id()][$age][$field_name][$entity_type_id][$entity->id()] = $entity;
                break;
              }

from file_get_file_references() will fail