The silent drift between what your API says and what it does

Every API-first team eventually runs into some version of the same OpenAPI problem.

The spec is accurate when somebody writes it. A month later, it probably still looks accurate too, because most API changes aren't big breaking changes. They're small things.

Someone adds a field to a response. A backend change needs to get out quickly, so it gets made directly in the handler. The deadline was yesterday, everything still works, and updating the OpenAPI spec gets missed.

Nothing broke, so nobody notices.

At least not yet.