Mining is extremely competitive, and every possible incentive is continuously explored to gain an edge. Even publicly traded miners are engaging in MEV: https://www.coindesk.com/business/2023/09/27/bitcoin-miner-marathon-reportedly-mines-invalid-btc-block/
"We utilize a small portion of our hash rate to experiment with our development pool and research potential methods to optimize our operations."
This is a transparent admission of MEV in action.