we can't see the notice. so the following is a guess. if you did not indicate to Turbotax that you got the payment, Turbotax would have calculated the credit which would show up on line 30 and increase your refund. the IRS computers show that you previously got it so the line 30 amount would have been reduced or eliminated reducing your refund
the only way to verify if you got it (the IRS computers say you did but some threads by OPs claim they did not despite what the IRS says) ) is to check your banking statements.
could have been around mid-March of 2021