'#autocomplete_route_name' does not work properly

chr.fritsch → made their first commit to this issue’s fork.

Drupal 9.5.9
php 8.1

I am getting this issue which is not caused by the patch.

Warning: Undefined array key "#autocomplete_route_name" in Drupal\select2\Element\Select2::setAutocompleteRouteParameters() (line 368 of modules/contrib/select2/src/Element/Select2.php).
Drupal\select2\Element\Select2::setAutocompleteRouteParameters(Array)
call_user_func_array('\Drupal\select2\Element\Select2::setAutocompleteRouteParameters', Array) (Line: 318)

Array:49 [▼
  "#title" => Drupal\Core\StringTranslation\TranslatableMarkup {#5709 ▶}
  "#description" => Drupal\Core\StringTranslation\TranslatableMarkup {#10687 ▶}
  "#field_parents" => []
  "#required" => false
  "#delta" => 0
  "#weight" => 0
  "#element_validate" => array:1 [▶]
  "#key_column" => "target_id"
  "#type" => "select"
  "#options" => array:1 [▶]
  "#default_value" => []
  "#multiple" => false
  "#cardinality" => -1
  "#select2" => array:2 [▶]
  "#after_build" => array:2 [▶]
  "#target_type" => "group"
  "#selection_handler" => "social"
  "#selection_settings" => array:3 [▶]
  "#autocomplete" => "1"
  "#suffix" => "<div id="group-selection-result"></div>"
  "#ajax" => array:3 [▶]
  "#field_name" => "groups"
  "#parents" => array:1 [▶]
  "#tree" => true
  "#input" => true
  "#sort_options" => false
  "#sort_start" => null
  "#process" => array:3 [▶]
  "#pre_render" => array:3 [▶]
  "#theme" => "select"
  "#theme_wrappers" => array:1 [▶]
  "#autocreate" => []
  "#empty_value" => ""
  "#value_callback" => array:2 [▶]
  "#defaults_loaded" => true
  "#array_parents" => array:2 [▶]
  "#processed" => true
  "#attributes" => array:6 [▶]
  "#title_display" => "before"
  "#description_display" => "after"
  "#errors" => null
  "#id" => "edit-groups"
  "#name" => "groups"
  "#value" => []
  "#ajax_processed" => true
  "#attached" => array:2 [▶]
  "#cache" => array:3 [▶]
  "#sorted" => true
  "#after_build_done" => true
]

i also get this issue, 🐛 'Render #pre_render callbacks must be methods of a class that implements \Drupal\Core\Security\TrustedCallbackInterface or be an anonymous function. T Needs review

Drupal\Core\Render\Renderer->doTrustedCallback(Array, Array, 'Render #pre_render callbacks must be methods of a class that implements \Drupal\Core\Security\TrustedCallbackInterface or be an anonymous function. The callback was %s. See https://www.drupal.org/node/2966725 → ', 'exception', 'Drupal\Core\Render\Element\RenderCallbackInterface') (Line: 788)
Drupal\Core\Render\Renderer->doCallback('#pre_render', Array, Array) (Line: 374)

I wonder if this might be the root cause