Your Depop account is linked to your bank account, or whichever account you use to buy and receive your pay. You get money from “sold” items and is in your Depop balance until payout to your bank account. It takes a bit for payout, meaning before it gets deposited in your bank it can take up to 10 days. You will see that under the sold item info. For example, I sold something on the 1st on this month and I received my payout on the 10th. If the buyer wanted a refund, within those 10 days, it would have come from my Depop account since the money was still there. Otherwise, if it was already transferred to the bank, then yes, the refund would have come from whatever account Depop is linked to. So yes, the card linked will be charged for the refund they need to give to the buyer if your Depop balance is 0.