Can MEV Occur on non-Proof-of-Stake (PoS) Blockchains?

Yes, MEV was originally identified and is still prevalent on Proof-of-Work (PoW) blockchains like pre-Merge Ethereum. In PoW, the miners extracted MEV by reordering transactions within the blocks they mined.

The transition to PoS simply shifted the power to extract MEV from miners to validators. Any blockchain where transaction ordering is not strictly fixed or randomized is susceptible to some form of MEV.