We do not know why you are seeing different results from another source. We cannot see any of your information. We can tell you that if you enter your data correctly and completely in to TurboTax software you should get accurate results. TurboTax has no way to know if you enter something incorrectly, leave out income, etc.
check your form 1040 line 30 for a non-zero amount.
TurboTax has been seen to put an amount there that should not be there.
line 30 is used only if you did not get your stimulus payments.