The marketing here trick is, if they spent the same money on humans they'd have found it years ago.
Instead, the lurking variable here is new budget was added. With the new budget, they added a new tool, and the bug was located.
The difference here was budget.
the budget for allowing a single engineer to deep dive on a bug that is annoying but also not bad enough that you can live with it for years is pretty big. $10k a month or more. My budget for Claude is $200/mo.