OP_RETURN: One of the most serious BTC controversies

Bitcoin, as a consensus, does not necessarily rely on a single dominant client software.

Written by: Liu Jiao Lian

Recently, a proposal to remove the size limit on additional data carried by OP_RETURN in the Bitcoin Core client has caused a stir in the industry. Typical proponents like developer Peter Todd have repeatedly submitted PRs (Pull Requests), showing a determination to not give up until their goal is achieved.

On July 23, 2023, Peter Todd submitted PR#28130, proposing to remove the restriction on data carried by OP_RETURN. The PR was closed and not adopted.

On April 28, 2025, he did not give up and submitted the same content proposal PR#32359 again. He aggressively demanded not only to remove the additional data limit but also to delete the configuration options to prevent client software users from opening the limits themselves.

The proposal was opposed by the majority.

Another developer, instagibbs, proposed a slightly more moderate suggestion PR#32406. He suggested temporarily keeping the configuration option but not imposing restrictions by default.

This proposal is also a step to praise BitZan. instagibbs has also written an explanation for this, detailing the origin of OP_RETURN and why such a change is being proposed.

Typical opponents include developer Luke Dashjr. He is the maintainer of the Bitcoin Knots client software and strongly opposed inscriptions two years ago. Specifics can be reviewed in previous articles by the teaching chain.

For the average reader, to simply understand this issue, the teaching chain can make such an analogy:

Remove additional data restrictions + Virtual machine executes additional data = Ethereum

Of course, it's not that simple in reality. The ledger of Bitcoin is a stateless UTXO model, and transforming the ledger to store state data (which brings the new problem of state explosion) would bring it closer to Ethereum's design.

In any case, it was because Bitcoin Core rejected Vitalik Buterin's proposal to utilize the additional data capabilities of the Bitcoin ledger to achieve his vision of smart contracts that forced him to establish the Ethereum project.

In this cycle so far, those betting on Ethereum to outperform BTC must have quite a few prairie animals racing past in their minds.

Since this capability is just a feature of the client software and not part of the Bitcoin protocol Consensus, there is no need to worry that this dispute will lead to a hard fork like that of 2017.

The main reasons for support include, for example, that there are many magic clients that have already removed this restriction and are supported by certain mining pools; Maybe it could bring more incentives to miners; Restricting the ability of OP_RETURN can't stop people from cleverly using other capabilities such as multisig and taproot script to carry data, but because of the restriction of forcing splitting and splicing data, it leads to the fragmentation of UTXO; There is no one-size-fits-all method to accurately identify what junk data is, which is destined to be a futile cat-and-mouse game; Wait a minute.

The main reasons for opposition include: lifting data restrictions may cause the Bitcoin ledger to swell rapidly, thereby weakening decentralization; it brings a large number of non-financial applications, diluting the positioning of BTC, reducing it to a mere checkbook; and so on.

According to Clark Moddy Bitcoin's statistics, the current size of the Bitcoin blockchain is approximately 748.1GB, with OP_RETURN additional data being about 3.83GB, accounting for approximately 0.5%.

There is currently no definitive conclusion on whether the related PR will be merged and released. However, based on the results of the community's voting with their feet, the number of nodes using the slimmed-down version of Bitcoin Knots has now surpassed the number of nodes running 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 is a fact, many people are simply not aware of it.)

A diversified Bitcoin ecosystem, with two to three equally matched Bitcoin client software, codebases, and developer maintenance teams competing against each other, adhering to a set of Bitcoin consensus, harmoniously different, contending without breaking, doesn't it instead highlight the charm of Bitcoin's decentralization?