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 writer of the proposal to elevate this coverage restrict.
The OP_RETURN coverage restrict was launched as a nudge to price restrict the quantity of arbitrary knowledge revealed onchain. By tolerating some small quantity of arbitrary knowledge publication (as much as 80 bytes) via the general public relay community, it will incentivize builders of purposes wishing to publish arbitrary knowledge to adapt their software program to those limits somewhat than constructing other ways to achieve miners.
This restrict turned out of date when customers began exploiting the witness low cost to retailer arbitrary knowledge in transaction witnesses. This technique is known as “inscriptions” and permits to retailer near 400kb of knowledge (i.e. 5000x extra knowledge than customary OP_RETURN outputs). These “inscriptions” created a development and shortly turned the primary 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 subsequently 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 alternate options. Subsequently whereas the OP_RETURN restrict specifically was made out of date by inscriptions, nudging with paternalistic coverage limits typically was made much less efficient as an utility builders now has entry to many alternate options to entry the block chain.
A very good instance of this dynamic is the latest “sub 1sat/vb summer time” development. Bitcoin Core has for a decade solely ever relayed transactions paying a feerate of at the very least 1sat/vb. This was some of the well-known and accepted relay coverage restrict. Through the summer time of 2025 various 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 point out 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 in any case 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 at the present time the easiest way to make sure quick and strong propagation to nearly all of miners. That is a necessary property for second-layer protocols (just like the Lightning Community), whose safety depends on having the ability to get a transaction confirmed in a well timed method.
If it was the case that some utility wished to retailer arbitrary knowledge 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 truly be counterproductive! It will create an incentive for such customers to masquerade the info they wish to publish as actual, spendable, transaction outputs. This manner they will nonetheless publish the info 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 presupposed to be doing! The OP_RETURN coverage restrict was not serving its supposed goal 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 knowledge 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 info they wished to publish as spendable outputs! This supplied 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 relies on utilization patterns on the community. As an 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 might 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 can occur, and i feel bandwidth utilization will likely be unaffected.
Doesn’t uncapping by default create potential authorized dangers for operators pressured to retailer arbitrary or illicit knowledge.
No. There could also be threat related to a Bitcoin node, since you can’t forestall the storage of arbitrary knowledge. These dangers aren’t materially affected by this transformation, if solely as a result of for something that may be saved in a 100KB OP_RETURN output, one thing 4x larger (and subsequently doubtlessly extra dangerous) can already be saved in a 400KB inscription. It will use a special 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 accomplish that in the present day at minimal price. Once more, relay coverage aren’t appropriate to counteract how block house will get used.
Would not threat 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 knowledge can already use inscriptions which might be 4x cheaper to make use of for a similar quantity of knowledge, and in addition enable to retailer as much as 4x the quantity of knowledge.
For extra in regards to the implication of this transformation, please see this reply.
