I can see how this will go. You won’t be able to access the IRS website to make a payment, but you’ll be liable for a late-payment penalty.
My son's girl friend is having a similar problem with her bank. Her car payment is set up on "auto debit". The agreed amount is supposed to be taken from her account on a specified day each month. The bank failed to do the debit, then claimed she was late on the payment and added "late" charges.
No paper records to contradict the ever-changing digital reality.