Your reward is the sum of the current validation fee minus the commission DePool charges for providing the service.
The validation reward depends on the blockchain settings, the number of transactions, and the stability of the DePool validator. The reward rate is flexible and change each cycle. The actual current annual reward rate can be found at ton.live/landing.
DePool commission fee is determined by the validator and can range from 1 to 99%. In Surf, the commission fee is 8%. All DePool fees can be found at ton.live/depools.
If the validation reward is 5.5% and the DePool fee is 8%, then you will receive for staking 5.5*0.92=5.06% annual income from your contribution.
To find out how much your current staking reward in Surf is, tap on the Earn staking rewards card on the application's home screen, or tap Assets Balance → Services → Staking.
Your staking reward begins to accrue from the next 18-hour validation cycle. Your crystals, including your initial deposit and accrued reward, will be credited to the wallet account within 54 hours (3 validation cycles).
Read more how to withdraw funds from staking.