Yes look over your whole return and see how it adds up. It's not the length of time you worked as 1099 but the total income. Your 1099NEC income is self employment. They didn't take any taxes out of it. Did you enter any expenses for it? The Net Profit adds to your W2 income. Then the Standard Deduction or your Itemized Deductions are subtracted giving you the taxable income on line 15. The tax on your income is on line 16. That is your income tax.
But then you also owe self employment tax on your Net Profit giving you the total tax on line 24.
Then your withholding (lines 25) and any credits are subtracted from the tax giving you a refund or a tax due for more. You came up short. When you have self employment income you needed to send in some extra tax for it since they didn't take any withholding out for you.
Before filing, You can preview the 1040 or print the whole return
https://ttlc.intuit.com/community/accessing/help/how-do-i-preview-my-turbotax-online-return-before-f...
How to get a copy after Efiling or printed for mailing.
https://ttlc.intuit.com/community/my-tax-return/help/how-can-i-access-my-return-after-i-ve-e-filed-o...
