Key takeaways
The Signal Is The Fingerprint
A Bitcoin-dev mailing list thread has turned an old fee-bumping feature into a privacy debate. RBF is not leaving Bitcoin. The narrower question is whether wallets should keep broadcasting the legacy BIP125 opt-in signal now that full-RBF behavior makes unconfirmed transactions practically replaceable across the network.
The proposal began with Bitcoin Core wallet work to remove explicit BIP125 signaling from ordinary wallet transactions. The author argued that the signal became redundant after full-RBF became default in Bitcoin Core nodes. That matters because BIP125 signaling is not a label floating outside the transaction. It is expressed through each input's nSequence value, so every transaction still has to reveal some choice. The old toggle survived because it once carried useful intent. The problem is that yesterday's intent marker can become today's surveillance feature.
Uniformity Beats A Toggle
Murch pushed the conversation toward the real design problem: wallets cannot simply delete a field. They must converge on one sequence value, or different wallet families will leave different on-chain fingerprints. The common candidates are final, non-final, and explicitly replaceable sequence values, with MAX-2 already common among wallets that signal replaceability.
That is why the debate is less about user preference than ecosystem camouflage. If Bitcoin Core, Sparrow, Electrum, hardware wallet coordinators, mobile wallets, and exchange wallets all pick different defaults, chain analysts get a cheap clustering signal. If they converge, ordinary users receive a privacy gain without needing to understand sequence arithmetic.
The Electrum Complication
Electrum maintainer SomberNight added the practical wrinkle. Electrum has used MAX-2 by default for most normal transactions for years, partly to mimic Bitcoin Core wallet behavior and reduce fingerprinting. But Electrum still treats the old signal as useful internal coordination for multi-device wallet contexts, including cases where only the originating device should safely fee bump.
That creates a tradeoff. A public sequence value can leak a small wallet fingerprint, yet removing the signal from wallet logic can make some recovery and multi-device situations harder. The thread even notes that the Core pull request was closed after feedback, which makes this a standards conversation rather than a finished policy change. The useful outcome would be a boring one: wallet authors agreeing on common behavior before divergent defaults harden into recognizable patterns. That kind of coordination is slow, but it is exactly how base-layer privacy usually improves. The defense is social before it becomes software.
Why It Matters
Bitcoin privacy often improves through dull uniformity rather than dramatic features. CoinJoin, address hygiene, and self-custody receive more attention, but the same incentive applies here: when ordinary wallet transactions look more alike, surveillance companies lose one cheap sorting mechanism. RBF already gives users a settlement mechanism for fee pressure, and full-RBF means the network increasingly treats replaceability as normal. The risk is letting old compatibility signals become permanent metadata. A shared sequence-value best practice would not make Bitcoin private by itself, but it would remove one unnecessary leak while preserving the fee-bump behavior users still need during congested mempools.
