She is not chewing on anything in her mouth but looks like she is? Is it her reflection?
She's been trying to get behind her litter box, even though there's nothing there, and has chewed through several of these floor mats and all of the layers of the carpet under them(only in one particular spot though). She doesn't do this every day but fixates on it for a few days at a time when she does.
by Thatpersonoverth3re