Then consider the movement of funds in and out of rollups.For optimistic rollups, when you want to withdraw funds, there is a ~1 week challenge period during which your withdrawal is frozen. This sucks. So to facilitate “fast withdrawals,” market makers will stand ready to move your assets quickly across the boundary—for a fee. The fee they charge you will depend on their inventory and the liquidity of the asset. If you’re moving ETH, this will cost maybe 0.2% or something, but if you’re trying to move a random dog coin, it will likely cost much more, possibly 1% or higher. Some assets may not be possible to fast-withdraw at all if there’s not enough liquidity.