Q. Do these numbers even sound right?
A. No.
If her $3400 of income was reported on a form 1099-NEC, TurboTax will treat that as self employment and "self employment (social security & medicare) tax" (SET ) will be due. But still not $1600.
Otherwise, you are correct $3400 of W-2 wages + $5334 of taxable scholarship is not enough (less than $12,550) to generate any income tax. You've entered something wrong. Review form 1040 and schedule 1 to see where it is being reported. Both wages and taxable scholarship should show up on line 1 of form 1040.
