Layer 2 Withdrawal Times: Finalized Stamp Lags Behind Actual Fund Arrival

A critical issue has been discovered in Layer 2 networks, affecting the withdrawal times of funds from these platforms to Ethereum. The problem lies in the discrepancy between the 'finalized' stamp displayed on the blockchain and the actual time it takes for funds to arrive on Ethereum.

Researchers measured the waiting periods on six Layer 2 networks and found that while the 'finalized' marker may indicate a withdrawal is complete, the funds can take anywhere from just under two hours to over ten days to arrive. This gap is due to the fraud window, which allows other participants to object to a transaction even after it has been deemed finalized.

The study focused on two types of Layer 2 networks: optimistic rollups (Arbitrum One, OP Mainnet, and Base) and zero-knowledge (ZK) networks (zkSync Era, Linea, and Scroll). Optimistic networks have a longer fraud window, which can take up to seven days, while ZK networks have no fraud window but require the execution of proof on Ethereum before funds can be claimed.

The discrepancy in withdrawal times is crucial for users who regularly move funds between Layer 2 platforms and Ethereum. This issue highlights the need for clearer communication about withdrawal times and the importance of understanding the underlying mechanics of these networks.