Base has retired its Flashblocks feeds, which now connect but transmit no data, forcing developers to migrate their data sources and subscriptions. The change follows the replacement of preview blocks with complete blocks every 200 milliseconds through Base's Denim upgrade. Developers relying on the deprecated Flashblocks infrastructure must update their integrations to maintain access to real-time chain data. Base is directing affected builders to switch to alternative subscription methods aligned with the new block production cadence.