You do not have to use the 2021 Form 1040-ES vouchers if your 2021 income is not going to be as high as it was in 2020.
1040-ES vouchers are prepared as a courtesy, based on the assumption that your income and taxes are going to be similar in the next tax year. TurboTax does this to help you avoid future underpayment penalties.
Since you know that won't be the case, you don't need to use them. Just be mindful that your 2021 withholding (or other estimated payments) should be sufficient to meet your 2021 tax liability.
