Allow unregistered users to post embeded images from other sites in comments

To allow unregistered users to post embedded images from other sites in comments, you will need to modify wp comment handling to permit certain HTML tags for unregistered users. By default, wp sanitizes HTML input from unregistered users for security reasons.

You need to modify the list of allowed HTML tags in comments for unregistered users. You can use preprocess_comment wp filters

add code your functions.php file

// Allow unregistered users to post embedded images in comments
function allow_unregistered_users_to_post_images($comment_data) {
    // Check if the user is unregistered
    if (!is_user_logged_in()) {
        // Define the allowed HTML tags for unregistered users
        $allowed_tags = array(
            'a' => array(
                'href' => array(),
                'title' => array()
            ),
            'img' => array(
                'src' => array(),
                'alt' => array(),
                'title' => array(),
                'width' => array(),
                'height' => array()
            ),
            'br' => array(),
            'em' => array(),
            'strong' => array()
            // Add more tags if needed
        );

        // Set the allowed HTML tags for unregistered users
        $comment_data['comment_content'] = wp_kses($comment_data['comment_content'], $allowed_tags);
    }

    return $comment_data;
}
add_filter('preprocess_comment', 'allow_unregistered_users_to_post_images');

above code allow unregistered users to post embedded images <img> tags in comments. Adjust the $allowed_tags array as needed to permit other HTML tags or attributes