Why did my refund go down when I entered another W2?

I have four W2's for 2019. When I entered the fourth and final one (wages: $1,449.05), my refund went down by $111. I noticed that there was no federal income tax withheld on this W2, so not sure if that has something to do with it. The total income for 2019 with all four combined was $10,877. This is less than the $12,200 standard deduction, and my tax liability is listed as $0, so I am confused.  Why would the refund decrease if total income is less than the standard deduction and my tax liability should theoretically be $0?

Thanks!