OP Labs said on Twitter that the Bedrock upgrade will introduce a new two-step withdrawal process for the Optimism mainnet bridge, which will improve its security and make attacks more difficult.
The new withdrawal process for L1 is divided into two parts: proof and finalization. To withdraw funds from the Optimism mainnet, users must submit a withdrawal proof as soon as the output of the L2 block containing the withdrawal transaction appears on L1. On average, it takes about an hour for this output to appear on Ethereum. Once the withdrawal proof is submitted, the user waits for the standard 7-day end window before the user can complete the withdrawal on L1.
