Staking has a fixed APY.

You will earn a fixed APY on your staked amount.
YFDAI Staking APR:
APR-Yearly: 72%
APR-Monthly: 6%
APR-Daily: 0.2%
The Fees are also fixed. there's 1.5% fees for staking and 0.5% fees for unstaking.

These fees are collected and will be burned every quarter.