Vitalik Buterin is turning 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 decides 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 construction, the process of assembling transactions before finalizing them on the chain, from becoming too centralized.
While Ethereum’s upcoming “Glamsterdam” update will formalize the separation between proposers and builders, allowing validators to outsource block construction to a competitive marketplace, Buterin maintains that simply creating a builder marketplace doesn’t solve everything. If a small number of builders dominate, they could still censor transactions or extract huge profits from users.
One proposal, known as FOCIL, would act as a kind of anti-censorship backstop. According to the design, a small group of randomly selected participants would choose each of the transactions that should be included in the next block. If those transactions are missing, the block will be rejected. The idea is that even if a single hostile builder controlled the entire market, it couldn’t permanently exclude specific users.
Another focus of his publication is the so-called “toxic MEV”, where operators exploit the visibility of pending transactions to advance or “sandwich” users’ operations. One possible solution is to encrypt transactions until they are completed, preventing opportunistic actors from seeing them in advance.
Buterin also points out risks at the network layer, where intermediaries can observe transactions before they even reach a block, suggesting that anonymous routing systems could become an important line of defense.
Longer term, it outlines a vision of a more distributed block construction, where not all transactions require full global coordination. He argues that much of Ethereum’s activity may not need to be processed in a single tightly ordered packet, opening the door to designs that reduce central choke points.
Overall, Buterin seems to be focusing on that as Ethereum grows, decentralization challenges are shifting from validators to the infrastructure that decides which user transactions actually make it onto the chain.
Read more: Vitalik Buterin reveals his bold new plan to solve Ethereum’s scaling problem
