Unexpected tax refund

A couple weeks ago we received an unexpected refund from the IRS, the stated reason being, "Excess advance premium tax credit repayment."  While this is certainly a nice surprise, why didn't Turbotax figure the amount correctly in the first place? What else did it get wrong?  Does this mean I don't owe the amount deferred until Dec. 31, 2022, i.e. the amount on Schedule 3, line 13 and Form 1040, line 31?