Bitcoin developers are advancing BIP-54, a soft fork dubbed the "Great Consensus Cleanup," designed to fix four consensus rule vulnerabilities that have existed since the protocol's 2009 launch. The proposal targets time warp attacks, resource-intensive "poison" blocks, a 64-byte transaction flaw in the Merkle tree, and replay risks from duplicate coinbase transactions. First drafted by developer Matt Corallo in March 2019, BIP-54 received its formal designation in April 2025, with test vectors merged later that year and testing beginning on the Bitcoin Inquisition Signet network in February 2026. Mining pools MARA Pool and ViaBTC have already started producing BIP-54-compatible coinbase transactions on mainnet. Corallo estimates an approximately 80% probability that BIP-54 becomes Bitcoin's next soft fork after Taproot. The upgrade will not alter Bitcoin's economic model, supply schedule, or token structure but aims to reduce the network's attack surface. LayerTwo Labs' Paul Sztorc criticized the proposal as mere "cleanup work" that introduces no new features.