I am trying to make an Ajax request to the backend, but I get the error Uncaught ReferenceError: TYPO3 is not defined which is caused by this line :

const url = TYPO3.settings.ajaxUrls['do_something_identifier'];

Here is my Extension/Resources/Public/JavaScript/example.js :

import DocumentService from '@typo3/core/document-service.js'
import DebounceEvent from '@typo3/core/event/debounce-event.js';
import AjaxRequest from '@typo3/core/ajax/ajax-request.js';

DocumentService.ready().then(function () {
  new DebounceEvent('input', function (e) {
    const searchValue = e.target.value;
    const url = TYPO3.settings.ajaxUrls['do_something_identifier'];
    new AjaxRequest(url)
      .withQueryArguments({ search: searchValue })
      .get()
      .then(async function (response) {
        const resolved = await response.resolve();
        console.log(resolved.result);
      });
  }, 250).bindTo(document.querySelector('#html-element'));

})

And I call it from the HTML like this :

<f:section name="Main">
  <f:be.pageRenderer includeJavaScriptModules="{
     0: '@vendor/extension/example.js'
  }" />

Here is my Extension/Configuration/Backend/AjaxRoutes.php :

<?php

return [
    'do_something_identifier' => [
        'path' => '/extension/controller/do-something',
        'target' => VendorExtensionControllerExampleController::class . '::doSomethingAction'
    ],
];

Here is my Extension/Configuration/JavaScriptModules.php

<?php

return [
    'dependencies' => ['core', 'backend'],
    'imports' => [
        '@vendor/extension/' => 'EXT:extension/Resources/Public/JavaScript/',
    ],
];

Here is my Extension/Configuration/TypoScript/setup.typoscript

plugin.tx_extension {
    mvc.callDefaultActionIfActionCantBeResolved = 1

    view {
        templateRootPaths {
            10 = {$plugin.tx_extension.view.templateRootPath}
        }

        partialRootPaths {
            10 = {$plugin.tx_extension.view.partialRootPath}
        }

        layoutRootPaths {
            10 = {$plugin.tx_extension.view.layoutRootPath}
        }
    }
}

The offical docs mentions this :

.Since the route is registered in AjaxRoutes.php it is exposed to JavaScript now and stored in the global TYPO3.settings.ajaxUrls

Where is the problem exactly ?
Thank you in advance.