I'm not sure I understand the problem. You enter the negative amount from your 2021 Schedule D with a minus sign in front of the number. See the screen shot below.
I tried to recreate your situation in TurboTax. On the Let's get some info from your 2021 tax return screen, I was able to enter a negative number in the Allowable Loss box. The negative amount carried over into Schedule D.
If you transferred last year's TurboTax return over, you don't have to do a thing—we've already entered it for you.
Otherwise, follow these instructions:
[Edited 03-20-2023|5:40 AM PST]