Users' staked earnings are reflected by the increase of the amount of OKT the user can swap for with the stOKT they hold.
Suppose a user's exchange rate when staking is 1 OKT ≈ 0.99 stOKT, the user stakes 1,000 OKT, receives 990 stOKT.
Some time later, the exchange rate changes to 1 OKT ≈ 0.98 stOKT, now staking 990 stOKT would amount to 1,010.2 OKT.
Now the estimated earnings of the user would be 1,010.2 - 1,000 =10.2 OKT. If the user wants to unstake 990 stOKT, after the waiting period, they can claim 1,010.2 OKT all at once.