I think there's an argument for just accepting bikes sometimes creak.
Yeah I mean older, tired bikes will.
Modern stuff really shouldn't. It's a bad sign, means something is moving and that means something is wearing out and that thing might be integrated in to the frame...
Could be anything fastener related; Had a creak on my Habit - that has PF30.
It was the crank spider lock ring.
Had another creak.
It was one of the suspension bearings.
Had a 'tick under power' on my F-Si
It was the derailleur trying to wander off the hanger
etc.
As @platypus will attest to, I've also fallen for the fuck-this-bb-wait-it's-the-QR issue.