Yes, you will use code P when you amend your 2020 return. Enter the 1099-R as shown on the form with J and P. Ignore that it says taxable in 2019 in the dropdown. When you continue TurboTax will ask what year is on your Form 1099-R. Select 2021 and TurboTax will know that code P means taxable in 2020.
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