comment_notification_text filter for custom post type

Using comment_notification_text you will get comment notification text and comment ID.
To check the post type you need to get the post associated with comment and then you can check for post type

Example (Read the inline comments):

function custom_notificaion($notify_message, $comment_id) {
    $comment_obj = get_comment($comment_id); //Get comment object
    $comment_post = get_post($comment_obj->comment_post_ID); //Get post object
    
    //Check if it is your post type
    if (isset($comment_post->post_type) && $comment_post->post_type == 'your-post-type') {
        return __('Custom message here', 'text-domain'); //Return the custom message here
    }
    
    return $notify_message; //Return default message for rest of the posts
}
add_filter('comment_notification_text', 'custom_notificaion', 10, 2);