That is my suspicion, too.
Say 300k income (no itemization), and 75k in capital gains long term for 2019. (2018 income is 251,000).
How much is the total tax?
TurboTax is adding the 75k to the income making total income 375k. Total tax due looks like 28% on 375k instead of 28% on 300k and 15% on 75k.
