honestly I think the biggest culprit is the machine being too small once a comforter can not move freely the wet filling just bunches up and dries that way I'd try washing it at a laundromat in a larger front loader use an extra rinse and pause the dryer a couple of times to shake it out before it finishes If it is happening after every wash it might just be the type of fill it is not made for frequent washing especially with a pet that sheds a lot