Legendary Bitcoin developer Peter Todd has announced that full replace-by-fee (full-RBF) has become the default in Bitcoin Core v28.0. 

The RBF feature allows replacing unconfirmed Bitcoin transactions with different transactions that offer higher fees. It is generally used for fee bumping, cancelation, or updating transactions. 

While BIP-125 allows disabling RBF, full-RBF makes sure that transactions are always replaceable. 

The debates about full-RBF have been raging within the Bitcoin community for more than a decade. Bitcoin is known for being extremely conservative when it comes to implementing significant changes. 

Todd also argues that the transaction is good for miners due to profit-maximizing. Moreover, such a feature reduces legal risks that might arise from unconfirmed double-spends. When it comes to security, full-RBF eliminates the risk of an attacker pulling off a double-spend by slowing down propagation. 

Finally, full-RBF also increases privacy by making it more challenging for blockchain sleuths like Chainalysis to deanonymize transactions. 

According to Todd, it took full-RBF peering as well as a lot of marketing on his side in order to finally integrate the feature: 

“I think the #1 thing it took was forking Bitcoin Core for years with full-RBF peering code; #2 being token protocols accidentally creating an auction market paying thousands of dollars in fees to full-RBF miners.” He added that the revenue opportunity offered by the feature would have likely remained unnoticed without full-RBF peering.