Vitalik Buterin turns his attention to a part of Ethereum that most users never think about, but that has quietly become one of its biggest pressure points: who gets to decide which transactions go into a block.
In a new blog post on Monday, the Ethereum co-founder lays out a series of ideas aimed at preventing block building, the process of aggregating transactions before they are finalized on the chain, from becoming too centralized.
While Ethereum’s upcoming “Glamsterdam” upgrade will formalize the separation of proposers and builders, allowing validators to outsource block building to a competitive market, Buterin argues that simply creating a marketplace of builders won’t solve everything. If a small number of builders dominate, they can still censor transactions or extract larger profits from users.
One proposal, known as FOCIL, would act as a kind of anti-censorship backstop. Under the design, a small group of randomly selected participants would each select transactions to be included in the next block. If these transactions are missing, the block will be rejected. The idea is that even if a single hostile developer controlled the entire market, they couldn’t permanently exclude specific users.
Another focus of his post is so-called “toxic MEV”, where traders exploit visibility into pending transactions to front-run or “sandwich” users’ trades. One potential solution is to encrypt transactions until they are completed, preventing opportunistic actors from seeing them in advance.
Buterin also points to risks at the network layer, where transactions can be observed by intermediaries before they even reach a block, suggesting that anonymized routing systems could become an important line of defense.
In the longer term, he outlines a vision of more distributed block building, where not all transactions require full global coordination. Much of Ethereum’s activity, he argues, may not need to be handled in a single, tightly ordered bundle, opening the door to designs that reduce central choke points.
Overall, Buterin seems to be focusing on, as Ethereum scales, decentralization challenges shift from validators to the infrastructure that determines which users’ transactions actually make it onchain.
Read more: Vitalik Buterin Unveils His Bold New Plan to Solve Ethereum’s Scaling Problem
