The way you enter your 2021 Roth Contributions to establish your basis for not being taxed is collected when wrapping up the "IRA, 401(k), Pension Plan Withdrawals (1099-R)" section under "wages & Income". It's not very obvious in my opinion.
I ran into this same issue - I put in my 1099-R and my refund went WAY down. I spent an hour trying to figure out where to enter my 2021 Roth contributions. Finally decided to wrap up that section and come back later, and discovered that Turbo Tax collects your contribution amount as part of the final wrap up questions for that section. My tax liability was corrected upon entering the amount.
