Now on Ethereum, there is an interesting phenomenon where more and more decentralized exchanges (DEX) are having their trading volume not go through the public mempool, but instead sent directly to miners/builders through private channels to avoid being seen and exploited by others.

This also indicates that DEX is gradually maturing.

If using the public mempool, for example, clicking "swap" on a DEX, the user's trade is broadcasted to the Ethereum public mempool, which is a waiting area visible to everyone; at the same time, MEV seekers monitor the mempool in real-time, and if they see a large order from that user, they immediately front-run or perform a sandwich attack on the user. The user gets squeezed, causing discomfort and increased slippage.

MEV predators place a transaction before and after the user's trade, sandwiching the user's transaction in the middle. The first transaction buys the same token, driving up the price, the user's transaction executes in the middle, and they can only buy at the inflated price. Immediately after, the second transaction sells the previously bought token, pulling the price back down, thus profiting.

Mature DEXs often skip the public mempool; good wallets or aggregators default to using private RPCs (such as flashbots protect/eden network, etc.), so the user's trades are not broadcasted to the public mempool but are sent directly encrypted to professional block builders. After receiving private orders, builders try to refund a portion of the MEV profits, so they won’t be sandwich attacked. By 2025, large transactions on Ethereum in the public mempool have become increasingly rare.

So, what does this mean for ordinary users?

Using mature wallets/DEX + default RPC for exchanging tokens, generally, they won’t be sandwich attacked; slippage and gas fees are much lower than in the previous cycle, and they will receive a portion of MEV refunds; however, smaller transactions, such as those below 1000U, may still enter the public mempool, mainly due to the lower MEV profits.

Only one cycle has passed, and Ethereum's DEX has evolved from a public bidding environment where the highest gas wins the block and sandwich attacks are prevalent, to an era where more and more orders are going through private channels, with opportunities to reclaim rebates.