Does Turbotax calculate underpayment penalty for Virginia (ie Form 760c). Last year it did.

Yes, TurboTax is calculating the Virginia underpayment penalty using Form 760C.  I did a mock-up return and an underpayment penalty did calculate as a Virginia resident. The amount of the penalty will be next to the Start or Revisit Box on the Underpayment Penalty line. I have attached a screenshot below for further reference.

Virginia law requires that you pay your income tax in timely installments throughout the year by having income tax withheld or by making payments of estimated tax. If you do not pay at least 90% of your tax in this manner, you may be charged a penalty in addition to tax.

Your 2021 penalty may also depend on how much Virginia tax you paid in 2020. Please ensure you are entering the correct amounts on the page Last Year's Virginia Amounts.

For more information, please see 2021 Instructions for Form 760C.