Unlike BTC (transactions that confirm always succeed), Ethereum-family chains can EXECUTE-AND-REVERT, the EVM runs the transaction, charges gas, but reverts state if a contract assertion fails. Your user submitted a swap or NFT mint; it ran out of gas mid-execution or an OUTPUT contract rejected; gas is paid (you lose it), but no value was transferred. The user's wallet should NOT show the swap's intended debit, it never happened. The gas fee, however, was real. This lesson posts the gas-only entry that handles a failed Ethereum transaction.