A code 8J Form 1099-R for a distribution made in December 2020 would have nothing to do with a 2019 contribution. It would presumably be for a return of a contribution made for 2020. If you made a contribution for 2020 and then had it returned, you could the apply the excess from 2019 as a contribution for 2020, if you were eligible to make a Roth IRA contribution for 2020. (Note that TurboTax currently has an error-checking bug related to applying a prior-year excess as a current-year contribution.)
