Base’s Retired Flashblocks Feeds Accept Connections but Send No Data

Base has retired its Flashblocks preview feeds, which now accept connections but deliver no data after Denim switched to broadcasting complete blocks every 200 milliseconds. Developers must resubscribe to the new full-block stream and audit any logic that reads pending state, since the old preview channel no longer supplies updates. The change matters because applications relying on sub-second previews for transaction ordering, MEV strategies, or UI responsiveness could silently stall while appearing connected. Watch for reports of stale pending-state reads and for tooling and RPC providers to update their Base subscriptions to the 200-millisecond full-block feed.