Diagnosis
Yeah, this one's common. The fan in the air fryer lid is small and has to spin very fast to move enough air, so it's naturally loud. A high-pitched whine or a grinding noise, however, isn't normal.
How to Fix It
For just general loudness, there's no fix—that's how it's designed. Make sure the lid is fully locked into place on the base. If the noise is a new grinding or rattling, turn it off, unplug it, and let it cool. Check the air intake vent on the back of the lid for any large food debris (like a piece of breading or a pea) that got sucked in and is hitting the fan.
If That Didn't Work
If the grinding persists with a clear vent, the fan bearing might be failing. You can't really service that yourself. You'd need to contact Instant Pot support about the air fryer lid specifically.
Heads Up
The noise will be most intense during the initial preheat phase when the element is on full blast. It often quiets down a bit once it reaches temperature.