Here is a form using DI for $this->entity_type_manager

There is also a radio-button with Ajax (I have added the code as it is maybe the reason of my problem)

class myForm extends FormBase {    private ?EntityTypeManagerInterface $entity_type_manager=NULL;    public function __construct(DrupalCoreEntityEntityTypeManagerInterface $entity_type_manager) {      $this->entity_type_manager=$entity_type_manager;   }    public static function create(ContainerInterface $container) {     return new static(       $container->get('entity_type.manager'),     );   }    public function buildForm(array $form, FormStateInterface $form_state) {     // keep the value in $form_state to be used in submit     $form_state->set('entity_type_manager', $this->entity_type_manager);     ...     // Maybe the Ajax component is the problem     $form['container'] = [       '#type' => 'container',       '#prefix' => '<div id="ajax-wrapper">',       '#suffix' => '</div>',       'my_radio' => [         '#type' => 'radios',         '#options' => ["option1","option2"],         '#required' => TRUE,         '#default_value' => $type_of_bo,         '#ajax' => [           'callback' => [$this, 'ajaxGetInvestmentHandler'],           'wrapper' => 'ajax-wrapper',           'event' => 'click input',         ],       ],       ...     ];   }    static public function ajaxGetInvestmentHandler(array $form, FormStateInterface $form_state) {     return $form['container'];   }      public function submitForm(array &$form, FormStateInterface $form_state) {     // $this->entity_type_manager is NULL     // $form_state->get('entity_type_manager') is also NULL     ...   }    ...    } 

As you can see in the submit, $this->entity_type_manager is NULL and $form_state->get('entity_type_manager') is also NULL.

What is wrong?