TestTaskWithUserInput.php

<?php

namespace Drupal\menu_test\Plugin\Menu\LocalTask;

use Drupal\Core\Menu\LocalTaskDefault;
use Symfony\Component\HttpFoundation\Request;
class TestTaskWithUserInput extends LocalTaskDefault {
    
    /**
     * {@inheritdoc}
     */
    public function getTitle(Request $request = NULL) {
        return "<script>alert('Welcome to the jungle!')</script>";
    }

}