CSRF token is not varying in Ajax callback while submitting form

I have a form with ajax callback as following , on each submit token is not varying , it remains constant for all submit .

wall.routing.yml

wall.commentform:
path: ‘/commentform’
defaults:
_title: ‘Comment form’
_form: ‘DrupalwallFormWallCommentPost’
requirements:
_permission: ‘access content’
_csrf_token: ‘TRUE’

In from as following

WallCommentPost.php

$ajax = (
    'callback' => ($this,'_wall_comment_ajax_form_post'),
    'wrapper' => 'field-type-replace-comment',
    'event' => 'click',
    'progress' => array(
        'type' => 'throbber', 
        'message' => '',
        )
      );

$form(‘wall_submit’) = (
‘#type’ => ‘submit’,
‘#value’ => ‘Submit’,
‘#ajax’ => $ajax,
‘#prefix’ => ”,
‘#suffix’ => ”,
‘#attributes’ => array(
‘class’ => array(
‘btn’,
$ajax_class,
‘d-none’,
‘subbtn-‘.$nid
),
‘disabled’=>’disabled’
),
);
$url = Url::fromRoute(‘wall.commentform’);
#$token = Drupal::csrfToken()->get($url->getInternalPath());

$form('#action') = Url::fromRoute('wall.commentform')->setOption('query', (FormBuilderInterface::AJAX_FORM_REQUEST => 1,'token1' => $token))->toString();