Yea, I'd call that underemployed. Does that mean 80% of recent college grads are employed in their area of study? I would be shocked if that were true.
Underemployment in the Fed’s data is defined as working any job where at least 50% of people in the job field say you don’t need a college degree. So 80% of recent grads are working in jobs where the perception is you need a degree. Which with the insane requirements for entry level jobs could still be underemployment from a practical perspective