Hidden in the definition of sufficient is "meeting the standards for absolution that an investigator would use". I honestly see no reason a system could not go so far as providing case law references or FICO + ECOA guidance as evidence for a compliant rejection, even if the underlying reason is some statistics based on sex.

And why would a perfectly reasonable bank tell its customers it's using AI? AI would provide the breadcrumbs and the loan officer would conduct a reasonable story using that - it's just parallel reconstruction at its finest. I imagine this is how credit scores work. A number comes out of the system and the officer has the messy job of explaining it.

I used to work in munitions export compliance and there intent really matters. It's the difference between a warning and going to federal prison. And intent is just a plausible story with evidence to back your decision, once you strip the emotion away.