According to Foresight News, modular blockchain Celestia has announced support for Ethereum fallback functionality in the integration of OP Stack and Celestia. This feature enables Ethereum L2 (or L3) to 'fallback' to using Ethereum calldata for data availability (DA) in the event of a Celestia mainnet Beta downtime. Once the interruption is resolved, L2 will automatically resume publishing DA to Celestia. The Ethereum fallback mechanism is currently available in the celestiaorg/optimism v1.0.0 (OP Stack v1.0.0) version.