You can check your Solana staking rewards in the Phantom app.
Step 1. Click on the "Solana" token on the assets tab, and then select "Your Stake"
Step 2. Click on your Stake Account.
Step 3. Check the "Last Reward" section.
The rewards can not be withdrawn unless you unstake your SOL. Instead, the rewards are added to your stake (compounding), and you earn more SOL.
How to check all your Staking Rewards?
To see all the rewards, you can do this at solanabeach.io
Step 1. Paste your Wallet Address into the Search area
Step 2. Click on "Stakes"
Step 3. Click on an account
Step 3. Click on "Stake Rewards"
a. The "Epoch" number shows the reward amount and date.
b. You can click "Download CSV" and receive all the info as well, in spreadsheet form.