> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstack.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Chainstack updates: September 30, 2026

> On Arbitrum, Base, Arc, and Robinhood Chain, MEV protection is renamed to optimized submission.

**Add-ons**. On Arbitrum, Base, Arc, and Robinhood Chain, MEV protection is renamed to [optimized submission](https://docs.chainstack.com/docs/optimized-submission.md). Nodes that had MEV protection enabled now have optimized submission enabled.