According to @ItsDave_ADA, a Solana victim transaction that included a priority fee was front-run by an attacker transaction that appeared to pay no priority fee, as evidenced by the three Solscan transactions shared in his post. source: https://twitter.com/ItsDave_ADA/status/2009213026059079886 source: https://solscan.io/tx/UBgAKp7Fp5nVB5duHb72NDbksdSR9gu5e5hfe8fzLNWKAeNeoUPnr7c3tBJb4CLBQRF4vtX4nxyHC7wixwFmngV source: https://solscan.io/tx/3qmJ8CRJuoXudVeUBML8QfsBnXfW8tH6fiWWCVnEbVH83fPhqCjGg6HeTJPQ1o9jhdCE6ziUHkEypAY62XTf1fzf source: https://solscan.io/tx/BnWATXrcdbNWEHgJNjtCQFSqikTHcx3wXA2gfHvB1JUm91S1UJGMifMsZcCU5mBwqM8QBMqz2x4VZKGNoXcUD6J On Solana, priority fees are expressed as compute unit price and raise inclusion probability but do not guarantee ordering because leaders schedule transactions using multiple signals and local fee markets, so a lower or zero priority fee can still land earlier under certain routing and QoS conditions. source: https://docs.solana.com/developing/runtime-facilities/compute_budget source: https://docs.solana.com/transaction_fees source: https://docs.solana.com/cluster/stake-weighted-qos Direct submission to the slot leader via block engines or private relays, including Jito's block engine bundles, can place transactions ahead of public RPC order flow independent of priority fee level. source: https://docs.jito.network/block-engine/overview source: https://docs.solana.com/terminology Private or low-latency RPC routes that forward transactions directly to leaders, such as Direct-to-Leader services, can win ordering against public RPC even when the competing transaction pays a priority fee. source: https://www.quicknode.com/changelog/introducing-direct-to-leader-for-solana For traders, the actionable mitigations are to route orders through MEV-protected private submission endpoints or bundles to reduce frontrunning and sandwich risk. source: https://docs.jito.network/clients/mev-protect source: https://www.helius.dev/blog/introducing-helius-protect-private-transactions-on-solana Additionally, set a competitive compute unit price via the ComputeBudget instruction and use congestion-aware estimates so your transaction remains at the front of the local fee market when pools are busy. source: https://docs.solana.com/developing/runtime-facilities/compute_budget source: https://docs.solana.com/transaction_fees Finally, prefer validator-connected or direct-to-leader RPC for time-sensitive DeFi trades to minimize propagation delay and reduce adverse selection from MEV. source: https://www.quicknode.com/changelog/introducing-direct-to-leader-for-solana source: https://docs.jito.network/block-engine/overview