It's an inference model. It does not understand code no matter how much context it has. It can however output the most probable solution based on the context it has.

The first problem is they're letting AI touch their code.

The second problem is they're relying on a human to pick up changes in moved code while using git's built-in diff tools. There's a whole bunch of studies that show how git's diff algorithms are terrible, and how swapping to newer diff algos improves things considerably.

TL;DR on the studies:

• Only supporting add/remove/move operations is really bad.
• Adding syntax awareness to understand if differences in indentation should be brought to a reviewer's attention, improves code and makes code reviews more accurate. (But this is hard because it's language dependent)
• Adding extra operations (indent/deindent/move/rename-symbol/comment/un-comment/etc...) makes code review easier, faster and more accurate. (But again, most of this requires syntax awareness.

There's also a bunch of alternative diff algos you can use, but the best ones are paid, and the free ones have fewer features. See:

• https://www.gitclear.com/rich_diff_checker
• https://semanticdiff.com/
• https://difftastic.wilfred.me.uk/

They contained the impact. Root causing or “understanding” should come after impact mitigation. If needed find a safe way to reproduce the bug without customer impact.

We reverted the refactoring, deployed, un-banned the CEO, and set about analysis.

Yeah me too but if you keep reading they didn't actually "move on" in the way that it sounds.