BIP-54 proposes four fixes to longstanding weaknesses in Bitcoin’s consensus rules. The key is to separate the proposed changes from their activation on mainnet.
The first two address timewarp attacks that manipulate mining difficulty and costly legacy script checks that can slow block validation. The other two address ambiguity between 64-byte transactions and internal Merkle tree nodes, plus the handling of duplicate coinbase transactions. A coinbase is the special transaction that pays a block’s mining reward, not an exchange.
Existing rules already protect against duplicate coinbase transactions; BIP-54 proposes changes to their handling.
Some mining pools have begun producing BIP-54-compatible coinbase transactions. That is a preparation step. It does not mean the proposed rules are being enforced across mainnet.
A completed specification is also separate from activation.
Mainnet activation is still pending. Track both what BIP-54 would change and whether those rules have actually been activated.
