I say applicable because having a PhD in Chemistry is not being "over qualified" for entry level programming. But having 10 writing code could be interpreted as having more qualification than the job merits.

That's something you can optimize for. An overqualified engineer shouldn't take six months to earn their keep unless the codebase is a huge mess. If the overqualified engineer is worth the salary they're really qualified for, they'll be able to describe exactly what parts of the system need to get fixed so the next engineer can be patching code in much less time.

That's the problem you have to tackle as fast as possible. An overqualified candidate would be a good fit there: first task, streamline the onboarding problem. Document, test, document.