This is Alex from FastLane - we run the largest MEV relay for Polygon PoS. The FastLane system was designed to protect Polygon’s users from sandwich attacks - even those who don’t use any sort of private relay. FastLane protects users via the unoriginal disincentive mechanism of simply broadcasting all MEV bundles back into the public mempool; this exposes would-be attackers to each other, thereby adding significant risk of loss. Our goal is to keep Polygon PoS the best blockchain for users - both in terms of gas cost and execution quality.
To my knowledge, only ~1% of blocks are created by validators running an MEV system that protects sandwich bots.
We’ve been hearing reports of sandwich attacks occuring with greater frequency and are putting out a request for additional information. This is an active research area for us; we’re always looking for ways that bots could circumvent our system to attack users (so that we can fix the gaps by altering our disincentive mechanism). If you see any sandwich attacks, please post the victim transaction’s hash here so that we can investigate.