Th question is being asked with regard to all years prior to 2021. If you received Roth IRA distributions prior to 2021 totaling more than the amount of Roth IRA contributions made for years prior to 2021, your basis in Roth IRA contributions carried into 2021 is zero and all that remained in your Roth IRAs at the end of 2020 are amounts attributable to investment gains and possibly Roth conversions. (TurboTax will ask separately about your basis in Roth conversions.)
