Let’s say if the transaction tx_1 has one confirmation. But the tx_1 is fraudulent. Can it be rolled back? Here I am storing the confirmed blocks and if my transaction is in the block-1 then the confirmation of tx_1 is 1 and whenever the blocks come after the block-1 the confirmation will keep on incrementing. But after one confirmation, if the tx_1 is fraudulent then how to stop that transaction?