The Child Tax Credit is affected by the amount of your income.
Per IRS Publication 972 Child Tax Credit and Credit for Other Dependents, on page 4:
Limits on the CTC and ODC
The maximum credit amount of your CTC or ODC may be reduced if either (1) or (2) applies.
Modified AGI. For purposes of the CTC and ODC, your modified AGI is your AGI plus the following amounts that may apply to you.
If you do not have any of the above, your modified AGI is the same as your AGI.
AGI. Your AGI is the amount on line 11 of your Form 1040, 1040-SR, or 1040-NR.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.