Written by: Liu Jiao Lian
Recently, a proposal to remove the data size limitation for OP_RETURN in the Bitcoin Core client has caused a stir in the industry. Typical proponents like developer Peter Todd have submitted PRs multiple times, showing a determination not to rest until achieving their goal.
On July 23, 2023, Peter Todd submitted PR#28130, proposing to remove the data size limitation for OP_RETURN. The PR was closed and not adopted.
On April 28, 2025, he persisted and submitted the same proposal PR#32359 again. He aggressively demanded not only the removal of additional data restrictions but also the elimination of configuration options to prevent client software users from enabling the restrictions themselves.
The proposal received opposition from the majority.
Another developer, Instagibbs, proposed a slightly milder proposal PR#32406. He suggested temporarily retaining the configuration option but with no default restrictions.
This proposal has more criticisms than praises. Instagibbs even wrote an explanation for this, detailing the origin of OP_RETURN and why such a change was proposed.
A typical opponent is developer Luke Dashjr. He is the maintainer of the Bitcoin Knots client software and was a fierce opponent of inscriptions two years ago. Specifics can be reviewed in previous articles by Jiao Lian.
For ordinary readers, to simply understand this issue, Jiao Lian can use this analogy:
Remove additional data restrictions + virtual machine execution of additional data = Ethereum
Of course, it's not that simple. The Bitcoin ledger uses a stateless UTXO model, and to modify the ledger to store state data (which then leads to the new problem of state explosion) would bring it closer to Ethereum's design.
In any case, it was precisely because Bitcoin Core refused Vitalik Buterin's proposal to use the additional data capabilities of the Bitcoin ledger to implement the smart contracts he envisioned that he was compelled to establish the Ethereum project independently.
And during this cycle so far, those betting on Ethereum to outperform BTC must have quite a few grassland animals racing through their minds.
Since this capability is merely a feature of the client software and not part of the Bitcoin protocol consensus, there is no need to worry that this controversy will lead to a hard fork like in 2017.
The main reasons for support include: many modified clients have already removed this restriction and received support from some mining pools; it may provide more incentives for miners; restricting OP_RETURN capabilities does not prevent people from cleverly using other capabilities like multisig or taproot scripts to carry data, but rather, the restrictions may lead to fragmentation of UTXOs due to forced splitting and stitching of data; and there is no one-size-fits-all method to accurately identify what constitutes garbage data, making this a futile cat-and-mouse game; and so on.
The main reasons for opposition include: lifting data restrictions may lead to rapid inflation of the Bitcoin ledger, thereby undermining decentralization; it could bring about a large number of non-financial applications, diluting BTC's positioning and reducing it to a mere checkbook; and so on.
According to statistics from Clark Moddy Bitcoin, the current size of the Bitcoin blockchain is approximately 748.1GB, with OP_RETURN additional data accounting for about 3.83GB, or roughly 0.5%.
There is currently no definitive conclusion on whether the related PR will be merged and released. However, based on the community's voting with their feet, the number of nodes using the slimmed-down version of Bitcoin Knots has already surpassed the number of nodes using the latest version of Bitcoin Core 29.0.
Perhaps we will witness a historic moment: Bitcoin, as a consensus, does not necessarily have to rely on a single dominant client software. (Although this has always been a fact, many people just haven't realized it.)
A diversified Bitcoin ecosystem with two to three equally matched Bitcoin client software, codebases, and development teams competing with each other, adhering to a unified Bitcoin consensus, harmonizing differences, and fighting without breaking apart, may actually better highlight the charm of Bitcoin's decentralization.
