How can I get past years proof of federal tax payment?

Your only proof that you paid is your own bank or credit card record.   TurboTax never knows how, when or even if you paid the IRS.

TurboTax has no way to know when or if you paid taxes owed.

Your proof of payment is either the cancelled check you mailed to the IRS, your bank statement showing the debit for the IRS payment or your credit card statement showing the payment to the IRS.