It's not a TurboTax mistake. You answered Yes to the question that asked whether you or your spouse received or were approved to receive unemployment compensation in 2021. The box on line A at the top of Form 8962 should be checked. That automatically makes Form 8962 line 5 a fixed value of 133%. It is not calculated from lines 3 and 4. The 133% cutoff is a provision of the American Rescue Plan Act for 2021 only.
The 2021 IRS Instructions for Form 8962 say the following at the top of page 8.
"If you, or your spouse (if filing a joint return), received, or were approved to receive, unemployment compensation for any week beginning in 2021, enter 133 on line 5."
