You didn't say, but you probably have qualified dividends or long-term capital gain or both. Those are taxed at lower rates.
You also didn't say how you calculated the tax, or which line of Form 1040 you are referring to as "total federal tax." There are seven different methods that can be used to calculate the tax on Form 1040 line 16, depending on what types of income you have and other things in your tax return. The IRS instructions for Form 1040 line 16 explain the conditions for determining which of the 7 methods to use, starting in the right column on page 33 of the 2024 Instructions for Form 1040.
In TurboTax there is a Tax Smart Worksheet that has 7 checkboxes that show you which method TurboTax used. It's between lines 15 and 16 in the first section of the Form 1040 or Form 1040-SR Worksheet. If you do have qualified dividends or long-term capital gain TurboTax is probably using the Qualified Dividends and Capital Gain Tax Worksheet, or possibly the Schedule D Tax Worksheet.
Self-employment tax is not included in Form 1040 line 16. That gets added in later, on line 23, which comes from Schedule 2.
