Earlier quoted context omitted.
Until someone turned on logging of the full request body on the load balancer/proxy or otherwise unknown-to-you middlebox that was the TLS termination point in production that you did not know about
So their incompetence lies in lacking configuration management in production as opposed to a lack of testing? Why are they manually configuring production servers anyway at that scale?
That said, someone should have been watching for this stuff and failed to do so (or to exist), so I'm not excusing them - but this is not a trivial thing to protect against.