According to ChainCatcher, Arbitrum development team Offchain Labs is developing a defense mechanism titled "Adding relay client connection random numbers" to prevent MEV searchers from performing witch attacks on sequencers. This mechanism requires that random numbers must be unique between different clients, and relays will broadcast messages to clients in order from high to low random number target values, and the client with the highest random number target value will receive the message the fastest. If the random number target values ​​of two connections are the same, the client with the lower random hash value will receive the broadcast first, and then propagate it to other relays. (Source link)