When one of the correlated assets de-pegs and you believe the peg will be restored, you can take a leveraged position and arbitrage the difference in price between those assets. Let's imagine DAI > USDC.
Flash loans make it possible to arbitrage a peg within one block. Gearbox allows you to do so even if it takes more time. However, with stablecoins it's generally easier as there are other avenues to borrow from. But not for all pegged assets!