Solana client developer Jito Labs announced the discontinuation of its mempool functionality, a significant component of its technology stack, due to its association with "sandwich" attacks. Although Solana's core architecture does not incorporate a mempool, Jito's Block Engine, aimed at maximising extractable value (MEV) on the chain, implemented one. The decision to halt the mempool comes after a six-week confrontation between Jito and traders who exploited it for front-running transactions, leading to costly sandwich attacks. Despite Jito's prior ban on such practices in its mempool, traders continued executing these maneuvers, exploiting transactions awaiting confirmation. These sandwich attacks, more common in Ethereum due to high fees, became prevalent on Solana due to its low transaction costs, impacting retail users. Jito Labs recognized negative MEV, including sandwich attacks, as detrimental to the Solana ecosystem and opted to suspend the mempool, aiming to ensure a better execution environment for users and provide additional revenue streams for validators and stakers.