PIP-64: Validator-Elected Block Producer

[jerry]

@michael-lewellen

Granting a single producer control over multiple consecutive blocks (16 in this case) can amplify MEV opportunities.

@Tane

Multi-block MEV strategies could become highly lucrative and difficult to detect or prevent, potentially undermining transaction fairness and user trust.

@Thogard

To be clear, a single block producer currently has control over a sprint, which is 16 consecutive blocks. The producer can delay and capture multiblock MEV for a max of 8 of them (any more and their backup will reorg them).

It’s important to acknowledge that MEV extraction is possible within the existing Polygon PoS structure. Currently, a block producer has significant control over ordering and inclusion within their assigned 16-block sprint, including the ability to capture MEV across multiple blocks within that sprint (potentially up to 8 blocks before risking reorg by backups).

While the VEBloP model extends the duration a single producer is active, it isn’t immediately evident that this inherently makes malicious MEV significantly more lucrative or harder to detect compared to the existing sprint-based opportunities. A quantitative analysis, likely based on specific MEV modeling under both architectures, would be necessary to definitively assess the change in risk profile.

However, the centralization of block production does necessitate robust safeguards against potential MEV exploitation. PIP-65 outlined two layers of mitigation strategies:

1. Social Consensus & Off-Chain Coordination: In the immediate term, if a block producer is widely perceived by the validator set to be acting maliciously or unfairly exploiting MEV, validators can coordinate to trigger a producer rotation, effectively electing a new producer via Heimdall.
2. Future Automated Checks (Optional): Longer-term, the protocol could potentially incorporate basic MEV monitoring or heuristics during block validation. If detectable malicious MEV patterns exceeding defined thresholds are identified, the system could automatically trigger a producer rotation as an enforced protocol rule. Designing robust and manipulation-resistant automated checks remains an area for future research and development.

These strategies provide both immediate recourse through validator consensus and a path towards automated enforcement, ensuring mechanisms are in place to address potential abuses related to MEV.

@Thogard

From FastLane’s point of view, this would be a fundamental change from a bundle propagation architecture to a full proposer-builder separation design - the latter of which is strictly worse for users if left unchecked.

The elected block producer can continue working with Fastlane, similar to how validators are using Fastlane today. There aren’t changes to how transactions are propagated from this new architecture.