TypeAncestry always returns an empty array

[TheBnl]

I noticed that TypeAncestry always returns an array with one null item in it:

"typeAncestry": [
  null
],

While the method (DataObjectHashExtension::getTypeAncestry()) that is producing the array is actually creating the following array:

Array
(
    [0] => Array
        (
            [0] => UserDefinedForm
            [1] => b438700702fb871b886359357e938a87
        )
    [1] => Array
        (
            [0] => Page
            [1] => c989cfe250b1fadad5b45da5116401e3
        )
    [2] => Array
        (
            [0] => SiteTree
            [1] => 7a018541792aafd19ecdae03b3ad5ff5
        )
)

When changing the type from [[String]] to String and change the method so it returns the type directly it does return the actual type:

modelConfig:
  DataObject:
    type_formatter: 'SilverStripe\Core\ClassInfo::shortName'
    base_fields:
      ID: ID!
      HashID: String!
      TypeAncestry: 'String'
      # TypeAncestry: '[[String]]'
      exists: Boolean!

public function getTypeAncestry()
{
  $config = SchemaBuilder::singleton()->getConfig($this->owner->config()->get('headless_schema'));
  if ($config) {
    return $config->getTypeNameForClass($this->owner->ClassName);
  }
  return null;
}

returns:

"typeAncestry": "UserDefinedForm",

Is something changed in the way array types ([[String]]) are handled?
I noticed that in the silverstripe/silverstripe-nextjs your using a different implementation to determine the ancestry in the (Resolver::resolveStaticBuild() method)[https://github.com/silverstripe/silverstripe-nextjs/blob/db7b253217c0981a2b70203f26e0a90529ebfa4c/src/GraphQL/Resolver.php#L30] that uses a custom type TypeAncestry. Is that something that should be implemented here as well?

For context, i'm working on an sveltekit implementation where i would like to resolve a Page or Elemental template based on the ancestry. Currently i'm just directly falling back to Page when a template isn't found.