Vitalik Buterin proposed the FOCIL mechanism to address the centralized risks of Ethereum block building.

In his latest blog post, Vitalik Buterin focused on the centralized risks of Ethereum's block building process. He pointed out that even though the upcoming "Glamsterdam" upgrade will formally introduce proposer-builder separation (PBS), allowing validators to outsource block building to market-based builders, problems such as transaction censorship and excessive profit extraction may still arise if a few builders dominate. He proposed mechanisms including FOCIL, where randomly selected participants specify the transactions that must be included in a block, and the block is rejected if any are missing, thus reducing the possibility of censorship by a single builder. He also suggested mitigating the risks of preemptive strikes and pincer attacks caused by "toxic MEVs" through transaction encryption, and introducing anonymized routing at the network layer to reduce the risk of intermediate nodes observing transactions in advance.