1099-R Taxable Amount Not Determined

1099-R Box 2=Taxable Amount Not Determined. Box 7 Dist code=T.  2021 return.  This is for a Roth IRA, first withdrawal of $33K from the fund.  During TT input, TT pops my original investment of $25K, which leads me to think that $8K would be taxed. Instead, the TT Fed Tax summary showed no increase.  Total 2021 income is $100K+, so expected to see some Fed Tax added. Ideas??? TIA