This pool acts as a savings account denominated in USD where users lose a pro-rata share of LUSD deposits over time, while gaining a pro-rata share of the liquidated ETH collateral.
This pool is rated A due to its solid underlying asset and protocol. However, there is always the risk that ETH prices decline significantly (above the liquidation discount), which would result in a principal loss for users.
LUSD often trades more than 100bps off its peg to USD but is backstopped by the stability pool which ensures the total LUSD supply always remains collateralized.