I think TurboTax is correct: in the 2019 Instructions for For 8615, on page 3 it says that when completing the QDCGT Worksheet for line 7 there are additional caps for line 8 and line 15 of the worksheet. the cap for line 8 is (Form 8615, line 6 + $2,600) and for line 15 it is (Form 8615, line 6 + $12,950).
