When a client's deposit is refunded (you cancelled, they cancelled in time, or your late-cancel policy refunds some of it), the same amount is taken back from your Stripe balance, up to what you received for it.
Stripe does not return its card fee on a refund. On a full refund, that fee goes on your Money page and comes off your next payment.
If the refund is our fault (a payment that arrived after the time had gone, say), we pay that fee, not you.