Prior to the Tax Cuts and Jobs Act of 2017 you could get a miscellaneous deduction for any unrecoverable basis if your investments in your Roth IRA had lost value and you received distributions of your entire Roth IRA balance, so TurboTax needed to know your contribution and conversion basis and year end balance to know whether or not to include that deduction on your tax return. The suspension of this deduction expires after 2025, so TurboTax continues to ask for thin information so that TurboTax will have this information in the future when the deduction returns.
If you do not ever expect to claim this deduction, since your Roth IRA distributions are now qualified distributions you can omit your basis information since TurboTax doesn't need it to prepare your tax return.
