Yes, this is a bug in TurboTax. My notes show that I reported it back in 2016 and nothing was ever done about it.
If there is no reason for Form 8606 to be included in your filed tax return (no Part II or Part III), I suggest that after filing your federal tax return you override and correct line 14 of Form 8606 so that transferring your 2020 tax file into 2021 TurboTax to begin your 2021 tax return will transfer in the correct basis.