If you pay less than the minimum specified amount for the swap which is around 20-30 $.
It will trigger the underpaid status and you need to meet the minimum amount to continue or you can cancel the swap.
It is unclear how the smaller amount is sent for exchange, because it is indicated there when filling out. Previously, this problem was solved automatically. If the amount sent was less than the minimum amount for the exchange, it was automatically returned to the sender's address. Now the user has a choice, either to refund or to pay extra, which is more rational.
Those incidents happens when testing out the exchange, idk why they have to chose the almost minimum requirement amount to send. Anyway, this is good improvement, i never saw this feature in any exchange or any financial platforms. Usually those amounts sent below the minimum is considered as donations.
