Jessy, Jinse Finance
According to news on June 9th, Bitcoin core developers plan to release Bitcoin Core software version 30 in October, which will no longer filter OP_RETURN outputs containing large amounts of non-financial data. This change will increase the default data carrier limit from the current 80 bytes to nearly 4MB, while allowing node operators to manually modify the -datacarrier and -datacarriersize parameters.
As soon as this news broke, it immediately sparked heated discussions within the Bitcoin community. Proposal supporters believe this is a necessary step to release on-chain innovation potential, while opponents view it as a betrayal of Bitcoin's core values, with emotions so intense that some Bitcoin holders have even liquidated their positions.
The OP_RETURN expansion controversy has been ongoing for nearly two years. Although core developers plan to implement expansion in the Bitcoin Core software update in October, the dispute continues and this is not the final result.
What is expansion? Why does it cause controversy
The controversy first began in July 2023.
On July 23, 2023, core developer and expansion advocate Peter Todd submitted PR#28130, proposing to remove OP_RETURN data carrying restrictions, which was unsuccessful.
OP_RETURN is an opcode in Bitcoin script used to embed small amounts of data in Bitcoin transactions. It allows users to store data on the blockchain, but these outputs are "provably unspendable" and do not burden the UTXO set. Currently, Bitcoin Core's default limit is 80 bytes for OP_RETURN data, and transactions with OP_RETURN data larger than 83 bytes are limited by node policy rather than consensus rules.
On April 28, 2025, Peter Todd submitted the same proposal again as PR#32359, while instagibbs proposed a relatively moderate proposal PR#32406, suggesting temporarily retaining configuration options but with no default restrictions. On June 9th, Bitcoin core developer Gloria Zhao posted on GitHub stating that the Bitcoin Core 30 update planned for release on October 30th will remove the 80-byte limit for OP_RETURN functionality, allowing each output to carry up to 4 megabytes of data. Currently, the controversy triggered by this change continues, with significant divergence of opinions within the community.
The core argument of these expansion-pushing developers is that the current 80-byte limit hinders critical application development. For example, embedding data compliant with W3C verifiable credentials standards requires over 96 bytes of space, and enhanced Lightning Network atomic swap metadata and complex state proofs for RGB protocols may also be affected by the 80-byte limitation, preventing complete or efficient implementation of related functionalities.
This news reignited fierce debate within the Bitcoin community, with both sides holding firm to their positions. Opponents are also expressing protest through actions. On June 11th, Jason Hughes, vice president of the OCEAN pool, announced he would sell all his Bitcoin and exit the industry to protest the recent OP_RETURN change decision.
This expansion dispute, which has spread over nearly two years, always triggers extensive discussions whenever there are new developments, but most discussions revolve around disagreements within the Bitcoin Core development team and the resulting debates among extreme Bitcoin believers. Some developers believe that minor expansion is low-risk and beneficial, while another faction strongly opposes it, fearing sliding into functional bloat. Technical discussions quickly escalate into ideological conflicts.
Interestingly, mainstream mining pools and exchanges generally do not take a stance on this.
The Core of the Controversy: What is Bitcoin's Ultimate Role?
Supporters first start from Satoshi Nakamoto's original design intent, believing that the Bitcoin protocol in Satoshi's era had no data size limit for OP_RETURN. Removing the 80-byte limit is a return to Bitcoin's original spirit, consistent with its nature as an open system. Technology should remain open, with use cases determined by community innovation. The current 80-byte limit can be bypassed by directly submitting to miner mempool (like MARA Slipstream) or unrestricted nodes (like Libre Relay), rendering it virtually ineffective, so removing the limit would not actually introduce more risks.
On the other hand, expansion can also reduce network burden. Currently, protocols like inscriptions store data larger than 80 bytes through multiple transactions. After removing the limit, inscriptions can directly store data via OP_RETURN, reducing unnecessary multiple transactions and thus reducing network pressure.
Additionally, expansion can increase miner revenue. With Bitcoin's halving every four years reducing miner income, allowing large-size OP_RETURN transactions can enable miners to earn more by competing for block space, incentivizing continued hash power investment and consolidating Bitcoin network security.
Opponents' primary argument is that this move will occupy block space. Removing the limit might lead to more non-transaction data (like spam, low-value tokens) being written on-chain, occupying block space, thereby driving up transaction fees and affecting Bitcoin's efficiency and utility as a value transfer network. Moreover, this contradicts Bitcoin's design intent as a value transfer network and might reduce the blockchain to a data storage platform, straying from keeping Bitcoin "pure" for accounting rather than data storage.
Furthermore, Bitcoin Core removing configuration options (like -datacarrier and -datacarriersize) is seen as depriving users of their right to choose, adopting a "paternalistic" strategy, whereas retaining configuration options better aligns with Satoshi's decentralized "one CPU, one vote" philosophy.
The intense controversy essentially discusses Bitcoin's ultimate role in this world: Is it a pure, immutable "digital gold" and value storage foundation? Or a base settlement layer supporting limited but useful applications?
The OP_RETURN expansion touches this fundamental philosophical divide. Opponents believe any application attempts are a sacrilege to its "sanctity"; supporters argue that moderate evolution is the key to perpetuity. Times are changing, new public chains are emerging, and Bitcoin once again stands at a crossroads of choice.
