I checked this previous post, and here is my answers:

What template is being used? Does it modify the tpl_ajax_checkout_confirmation.php template?
Custom template based on responsive_classic template.
I cannot find "tpl_ajax_checkout_confirmation.php" in my site. Maybe this file is no longer used?

Is the paypaldp payment-method included in the OPC's "Payment methods requiring confirmation" list?
No.

What version of jQuery is being loaded for the site?
3.5.1

What version of PHP is in use?
7.4

Is the OPC's configuration setting "Debug: Customer List" set to a non-blank value?
No. It is blank.