If the Form 1099-R has code P in box 7, unless there is tax withholding shown in box 4 or there is state tax withholding the TT CPA is wrong that this is reportable on your 2020 tax return.
Assuming that the Form 1099-R has code P as expected, If your 2019 tax return does not show the $100 on Form 1040 line 4d, amend your 2019 tax return to include that. If the $100 is already present on line 4d, there is nothing to change on your 2019 tax return with respect to this.
