I paid my 2019 taxes through direct debit via TurboTax, and I have record of the withdrawal on my bank statement, but the IRS says they never received a payment.

Send the IRS a copy of your bank statement showing it paid.  Or maybe the IRS changed your return so you owe more?

TT doesn't pay the taxes ... it sends the debit info to the taxing authorities with your return  and the taxing authority  initiates the debit.  So if your bank/CC statement shows the correct payment then call the number on the notice and see if that can clear up the issue   OR  mail in proof of payment with your response to the notice.