Bitcoin News Today: Developer rkrux opened Bitcoin Core PR #35405 and posted to the Bitcoin-Dev mailing list on June 19, 2026, proposing to strip the legacy opt-in Replace-by-Fee (RBF) signal from wallet transactions, arguing that the BIP125 flag has become a redundant on-chain identifier now that full-RBF is the network’s default mempool policy.
This is not simply a code cleanup. It is a coordinated Bitcoin privacy initiative that requires cross-wallet alignment on a single default nSequence value, a problem that is more structurally complex than removing a flag.
rkrux posted to the Bitcoin-Dev mailing list proposing that wallets stop signaling opt-in RBF in the transactions they create…https://t.co/djmBbIubDG
— Bitcoin Optech (@bitcoinoptech) June 19, 2026
Bitcoin News Today: RBF Signal Removal: Why the Legacy Flag Now Creates More Risk Than It Resolves
Under BIP125, a transaction was considered opted in for replacement if any input carried an nSequence value below 0xffffffff − 1, a mechanism introduced in Bitcoin Core 0.12.0 in February 2016 to enable voluntary fee bumping of unconfirmed transactions without disrupting first-seen mempool behavior across the network.
Bitcoin Core’s subsequent shift to full-RBF as default policy, begun with the mempoolfullrbf option added in version 24.0 and later made the unconditional default, rendered that signal operationally inert. As rkrux stated in the mailing list post: “The primary reason for its removal is because ever since full-RBF became a standard policy, this signaling has become redundant.” Nodes running current default policy will replace any transaction regardless of its nSequence values, per Bitcoin Optech’s RBF topic documentation.
A decade old Bitcoin transaction flag became dead code 20 months ago. Bitcoin Core contributor rkrux wants wallets to stop setting it. The reason is privacy.
Replace by Fee lets you bump a stuck Bitcoin transaction’s fee after you’ve already broadcast it. BIP 125’s opt in… pic.twitter.com/CvIlt3vQqa
— Taurus (@Taurus4BTC) June 22, 2026
The residual cost of keeping the signal is wallet fingerprinting. Because the nSequence field is mandatory, wallets cannot leave it empty, any wallet that removes the BIP125 flag without coordinating on a replacement value will produce transactions with a distinct sequence pattern, making them identifiable on-chain. The concern is directly analogous to the on-chain tracking patterns that surface in long-term holder behavior analysis, where wallet-level metadata leaks inform cycle positioning far beyond what participants intend to disclose.
Sequence Number Coordination: The Case for MAX-2 as Ecosystem Default
Community participant Murch, identified in Optech’s coverage as Gloria Zhao, described the core tension: “stopping to signal replaceability makes it sound like it’s a matter of dropping a fingerprint, but… every sender has to pick a sequence for every input.” The field must carry a value; the question is which value all wallets converge on.
Murch and Electrum developer SomberNight both favored MAX-2 as the standard default, a position reinforced by Optech’s data showing MAX-2 is already the dominant nSequence value across approximately 75% of Bitcoin transactions.
Switching to MAX-1 – a non-signaling value, was considered but set aside because it would make Bitcoin Core transactions visually distinct from the existing majority, creating a new fingerprint rather than eliminating one. The goal, as rkrux framed it, is for the wider wallet community to agree on “the one that’s agreed on by the wider wallet community as a best practice.”
🔴 Bitcoin developers move to strip RBF signaling, citing privacy leak and redundancy
Bitcoin developers are coordinating to remove replace-by-fee (RBF) signaling from wallet software. The explicit opt-in flag became redundant after the network adopted full-RBF as standard… pic.twitter.com/SRsQQMhk3v
— NewsTongue (@NewsTongueX) June 22, 2026
There is also a forward-compatibility rationale. A proposed future upgrade pairing nVersion=3 transactions with Package RBF semantics would reserve MAX and MAX-1 for distinct policy behavior, making MAX-2 the safer long-run default and reducing migration friction as those changes roll out.
Industry Implication: Merchant Zero-Conf Workflows and Cross-Wallet Scope
The change preserves full fee-bumping capability for users, the ability to replace an unconfirmed transaction with a higher-fee version is unaffected. What changes is the visibility of that optionality in the transaction structure itself. Merchant workflows that previously used the visible BIP125 opt-in flag as a proxy risk signal for accepting zero-confirmation transactions will need to treat all unconfirmed transactions as potentially replaceable by policy, which has been the accurate technical posture since full-RBF became the default.
We suspect the more consequential outcome is the cross-wallet coordination precedent. If Bitcoin Core merges the PR and downstream wallets follow by standardizing on MAX-2, the episode will represent one of the more orderly ecosystem-wide defaults alignments in recent Bitcoin development, a contrast to the fragmented rollout of full-RBF itself, which proceeded wallet by wallet over several years before achieving network-level coherence.
Disclaimer: Coinspeaker is committed to providing unbiased and transparent reporting. This article aims to deliver accurate and timely information but should not be taken as financial or investment advice. Since market conditions can change rapidly, we encourage you to verify information on your own and consult with a professional before making any decisions based on this content.
Daniel Frances is a technical writer and Web3 educator specializing in macroeconomics and DeFi mechanics. A crypto native since 2017, Daniel leverages his background in on-chain analytics to author evidence-based reports and deep-dive guides. He holds certifications from The Blockchain Council, and is dedicated to providing “information gain” that cuts through market hype to find real-world blockchain utility.
