I have issue to retrive post thumbnail with rest api – Blancer.com Tutorials and projects

i have two site. main site and blog site. both of them are wordpress. i want show my latest post from
blog site to main site. but I have issue to retrieve post thumbnail.
all thing is OK except Thumbnail.

wp_get_attachment_image_src(get_post_thumbnail_id($post['id']), 'thumbnail')

retrive false.

function display_latest_blog_posts() {
    ob_start(); // Start output buffering

    // Replace with the URL of your blog site
    $blog_site_url = 'http://www.blog.domain.com';

    // Get the latest blog posts using WP REST API
    $response = wp_remote_get($blog_site_url . '/wp-json/wp/v2/posts?per_page=3');
    $posts = wp_remote_retrieve_body($response);

    if (!empty($posts)) {
        $posts = json_decode($posts, true);

        echo '<div class="latest-blog-posts">';
        
        foreach ($posts as $post) {
            echo '<div class="post">';
            echo '<h2 class="post-title">' . $post['title']['rendered'] . '</h2>';
            echo '<p class="post-date">' . date('F j, Y', strtotime($post['date'])) . '</p>';
            
            if (has_post_thumbnail($post['id'])) {
                $thumbnail_url = wp_get_attachment_image_src(get_post_thumbnail_id($post['id']), 'thumbnail')[0];
                echo '<img src="' . $thumbnail_url . '" class="post-thumbnail" alt="' . $post['title']['rendered'] . '">';
            }
            
            echo '</div>';
        }
        
        echo '</div>';
    }

    $output = ob_get_clean(); // Get the buffered content
    return $output;
}

Does anyone know where the problem is?