You don't necessarily get a refund of the entire child tax credit. It's a credit that is applied against your tax for the year. Look at your Form 1040. The child tax credit is on line 28. If line 28 is $4,500 you are getting the full credit.
If you got monthly advance Child Tax Credit payments in 2021, those were advance payments of the credit. The amount you got in advance is subtracted from the credit on your tax return. So, for example, if your total Child Tax Credit is $4,500 but you got advance payments of $3,000, the remaining credit on your tax return will be $1,500.
