All balance due returns are on the back burner right now while the IRS concentrates on returns with refunds, processing the pile of 2019 returns they still need to attend to and putting out third stimulus checks all while continuing to be understaffed due to covid.
The account will be debited on or AFTER the date you selected WHEN they finally get around to processing your return which may take months. If the debit did not happen yet and you already paid online then it is possible they will not debit the account a second time. If they did then it could take months for them to catch the overpayment and refund the excess. All one can do is wait patiently.
