Yes, the total gain would be $11,990.
It was 100% business for both years? Are you sure you used the Standard Mileage Rate in 2021? If so, I'm not sure why TurboTax is coming up with the full sale price as the gain. You may want to review all of the vehicle questions, in case you entered something incorrectly (such as saying you used Actual Expenses the first year, and used Bonus depreciation or Section 179 to claim the full cost of the vehicle).
