The W2 has nothing to do with the 3,000 Child Tax Credit advance. You owe because you added more income and the withholding on it wasn't enough to cover the tax on your total income.
Because you only get one standard deduction no matter how many W2s you put in. Turbo Tax starts out by giving you the Standard Deduction. You entered more income when you entered the second W2 but you didn't enter more deductions. And each job only withheld taxes like it was your only job for the year. You might want to adjust your withholding. Also as you add more income you might not be getting as many credits as before like the EIC credit. And it was probably giving you the EIC credit until you went over.
See, https://ttlc.intuit.com/community/refunds/help/why-did-my-refund-drop-when-i-entered-a-second-w-2/00...
Then post more about your 3,000 advance. How many children? How much advance did you already get during the year? You only get the remaining half as a credit on line 28. It either increases your refund or reduces a tax due.
