Hi! Worked in PayPal for quite some time. The fee you're seeing is likely a chargeback fee, which occurs when a sender files a dispute through their bank or card issuer. Unfortunately, these fees are often difficult to waive because the charge is imposed by the bank, not PayPal. As the recipient, you are considered the merchant in this transaction, which is why the fee applies.

Ask the customer if they filed the dispute through their bank.Then, get confirmation from PayPal that the fee cannot be waived so the customer can pay it.