Bitcoin Core contributor rkrux has proposed stripping out the opt-in Replace-by-Fee signaling mechanism from Bitcoin wallets, arguing that the feature became redundant when Bitcoin Core version 28.0 made full RBF the default mempool policy back in October 2024.
What RBF signaling actually does, and why it no longer matters
Replace-by-Fee is the mechanism that lets you bump a Bitcoin transaction’s fee after you’ve already broadcast it. The opt-in version was formalized in BIP 125 between 2015 and 2016, and first shipped in Bitcoin Core 0.12. It worked by tweaking a specific field in the transaction called nSequence. If your wallet set this field to signal “I’m replaceable,” nodes would allow a higher-fee version to take its place in the mempool, the waiting room for unconfirmed transactions.
When Bitcoin Core 28.0 launched in October 2024 with full RBF enabled by default, the entire opt-in dance became pointless. Full RBF means any unconfirmed transaction can be replaced with a higher-fee version, regardless of whether the sender explicitly flagged it.
So the proposal, floated around June 16, 2026, is essentially asking: why are wallets still putting on the wristband?
The privacy angle most people are missing
Different wallets set the nSequence field differently. Some use the legacy opt-in signal. Some use what’s known as the MAX-2 value. Some do other things entirely. According to data from mainnet-observer, roughly 75% of transactions now use the MAX-2 signaling value, meaning most wallets have already converged on a de facto standard.
But that remaining 25% is a problem. When your wallet sets a distinctive nSequence value, it becomes a fingerprint. Chain analysis firms can use these subtle differences to identify which wallet software created a transaction, which can then be correlated with other metadata to narrow down the sender’s identity.
Community feedback from prominent developers reinforced this concern. Murch, a well-known Bitcoin Core contributor, and SomberNight from the Electrum wallet project both weighed in on the discussion, with the data suggesting that standardization across wallets would meaningfully reduce this fingerprinting exposure.
A cleanup, not a controversy
It’s worth noting what this proposal is not. It’s not changing how RBF works at the protocol level. It’s not altering consensus rules. It’s not removing anyone’s ability to bump fees. Full RBF is staying. What’s being removed is the vestigial signaling mechanism.
The proposal targets wallet-level behavior, specifically how Bitcoin Core’s built-in wallet constructs transactions before broadcasting them. Other wallet implementations would need to adopt similar changes independently, though the 75% convergence on MAX-2 suggests the ecosystem is already moving in this direction organically.
What this means for investors and the broader ecosystem
No immediate market impact has been reported as a result of this proposal.
The risk to watch is fragmentation. If major wallet providers don’t adopt the same approach, the fingerprinting problem could actually get worse for the minority that updates while others don’t. The current 75% adoption of MAX-2 is encouraging, but the final 25% will be the harder part of the migration.