TL; Dr: The standardness restrict on OP_RETURN outputs was lifted by default as a result of it did extra hurt than good.
Disclaimer: I’m the creator of the proposal to elevate this coverage restrict.
The OP_RETURN coverage restrict was launched as a nudge to fee restrict the quantity of arbitrary information printed onchain. By tolerating some small quantity of arbitrary information publication (as much as 80 bytes) via the general public relay community, it will incentivize builders of purposes wishing to publish arbitrary information to adapt their software program to those limits moderately than constructing other ways to achieve miners.
This restrict grew to become out of date when customers began exploiting the witness low cost to retailer arbitrary information in transaction witnesses. This technique is named “inscriptions” and permits to retailer near 400kb of information (i.e. 5000x extra information than normal OP_RETURN outputs). These “inscriptions” created a development and rapidly grew to become the principle driver of block house demand, producing tons of of hundreds of thousands of {dollars} in mining charges.
In the meantime, infrastructure was being constructed to make it simpler to bypass the general public relay community and due to this fact Bitcoin Core’s relay coverage. APIs to submit transactions on to miners, different peer-to-peer networks with looser relay coverage restrictions, and a broad curiosity from customers and builders to construct these options. Subsequently whereas the OP_RETURN restrict particularly was made out of date by inscriptions, nudging with paternalistic coverage limits normally was made much less efficient as an utility builders now has entry to many options to entry the block chain.
An excellent instance of this dynamic is the latest “sub 1sat/vb summer season” development. Bitcoin Core has for a decade solely ever relayed transactions paying a feerate of at the very least 1sat/vb. This was one of the vital well-known and accepted relay coverage restrict. In the course of the summer season of 2025 a lot of customers, builders and miners “memed” themselves into bypassing this restrict. In a short time, near half of all transactions included within the block chain have been transactions that no model of Bitcoin Core would relay by default. This simply goes to indicate how fragile coverage limits actually are, and that they’re unsuitable to counteract what will get included within the block chain.
Whereas the OP_RETURN coverage restrict was obsoleted by inscriptions, and whereas relay coverage limits are anyhow unsuitable for counteracting how block house will get used, they did do one thing. By definition, the OP_RETURN restrict prevents leveraging the peer-to-peer transaction relay community. Utilizing this community, whereas not essential to get entry to dam house, nonetheless has worth. It’s to this present day the easiest way to make sure quick and sturdy propagation to the vast majority of miners. That is a vital property for second-layer protocols (just like the Lightning Community), whose safety depends on with the ability to get a transaction confirmed in a well timed method.
If it was the case that some utility wished to retailer arbitrary information in non-witness components of a Bitcoin transaction whereas nonetheless benefiting from the properties of the peer-to-peer transaction relay community, the OP_RETURN coverage restrict would really be counterproductive! It could create an incentive for such customers to masquerade the information they wish to publish as actual, spendable, transaction outputs. This manner they will nonetheless publish the information in non-witness components of the transactions AND they will nonetheless profit from the properties peer-to-peer transaction relay community. A relay coverage that creates perverse incentives is horrible: that is the polar reverse to what it’s imagined to be doing! The OP_RETURN coverage restrict was not serving its supposed objective anymore, but it was created perverse incentives. From a principled standpoint, it needed to be lifted.
It’s the case that some utility wished to retailer arbitrary information in non-witness components of a Bitcoin transaction whereas nonetheless benefiting from the properties of the peer-to-peer transaction relay community. The Citrea bridge is an instance of that. And guess what, they began masquerading the information they wished to publish as spendable outputs! This offered additional proof that the OP_RETURN coverage restrict was now a legal responsibility and was the set off for my proposal.
The OP_RETURN coverage restrict did extra hurt than good and that’s the reason it was proposed to be lifted, and the proposal accepted.
Doesn’t uncapping by default improve the bandwidth and storage burden on each full node?
No. The storage burden is bounded by the consensus restrict on the block measurement. The bandwidth burden on a node depends upon utilization patterns on the community. For example if it was frequent to make use of OP_RETURN outputs bigger than 80 bytes and also you stored this coverage restrict by yourself node (with the -datacarriersize choice in Bitcoin Core), it may presumably improve the bandwidth burden of your node. Subsequently lifting the restrict on this case would scale back your bandwidth burden. However i do not suppose this may occur, and i believe bandwidth utilization can be unaffected.
Doesn’t uncapping by default create potential authorized dangers for operators pressured to retailer arbitrary or illicit information.
No. There could also be danger related to a Bitcoin node, since you can not forestall the storage of arbitrary information. These dangers will not be materially affected by this alteration, if solely as a result of for something that may be saved in a 100KB OP_RETURN output, one thing 4x larger (and due to this fact doubtlessly extra dangerous) can already be saved in a 400KB inscription. It could use a unique encoding, however this has no bearing on the legality of the saved content material. It is also the case that somebody malicious prepared to retailer nefarious content material in a big OP_RETURN particularly (for some cause) can already achieve this right now at minimal value. Once more, relay coverage will not be appropriate to counteract how block house will get used.
Would not danger mission drift by encouraging non-monetary use of Bitcoin’s scarce block house?
This modification doesn’t encourage non-monetary use of Bitcoin. Customers wishing to make use of Bitcoin to retailer arbitrary information can already use inscriptions which might be 4x cheaper to make use of for a similar quantity of information, and in addition permit to retailer as much as 4x the quantity of information.
For extra in regards to the implication of this alteration, please see this reply.
