Valley refers to the DUSD staking system. If the underlying stable-coins fall below their $1 peg, the DUSD system will become under-collateralized. To offset this risk, DUSD has a native staking mechanism. It’s possible to stake DUSD with the system which acts as additional collateral for the DUSD coins that are in free circulation (not staked). In the event of peg failure of the underlying stablecoin assets, the stakers act as buyers of the last resort in the DUSD system. For bearing this risk, stakers will receive all the underlying income generated from having deposited funds in Curve.