As of today it is possible to bridge USDC, ETH, and UMA from Arbitrum back to L1 Ethereum. The bridging function works by offering incentives for relayers to offer short-term loans to users on L1, which are repaid after two hours from a liquidity pool on L1. This pool is refilled when the funds arrive from L2 transactions. These transactions are insured by UMA’s Optimistic Oracle.
