Can an Arbitrageur’s Trade Itself Cause Impermanent Loss for Liquidity Providers?

Yes, an arbitrageur's trade is the mechanism that causes the impermanent loss to be realized. When the arbitrageur trades with the pool to correct a price imbalance, they are forcing the pool to rebalance its reserves.

This rebalancing is the action that shifts the pool's asset composition away from the initial deposit ratio, which is the definition of impermanent loss. However, the arbitrage trade also generates trading fees that partially compensate the liquidity providers.