Not easy to internet. If the sheetrock is that loose I would expect to see nail pops. I assume this is on an outside wall?

Yes indeed an outside wall. Creaks and pops on windy days. No wind, no creak. I can replicate the sound by pressing my hand against the wall.

And correct, zero nail pops.

When you look from outside the house, what do you see there? Is that there the exhaust fan vent happens to be in the roof or siding? My bathroom exhaust fan sometimes flaps on windy days.

Meghan, Outside wall. The exhaust fan vent is on the roof but is on the opposite side of the bathroom where the noise is coming from. I have hired an inspector for 11 month home warranty. Hopefully we can figure it out so the builder can repair under warranty.