The software is calculating an estimate of the amount needed to avoid penalty. You can increase of decrease that estimate based on your expected 2021 income. If you are not taking the SE deferral, then you can increase your payments by the correct amount for your situation.
Generally, most taxpayers will avoid underpayment penalty if they owe less than $1,000 in tax after subtracting their withholdings and credits, or if they paid at least 90% of the tax for the current year, or 100% of the tax shown on the return for the prior year, whichever is smaller.
IRS Estimated Taxes
