I just found this topic. I’m running the same frame and an Orange+.
The supplied anti-vibration pads
Removed with only thin silicone vibration bumpers.
I don’t yet have enough experience with PX4, but I believe there is a resonance being set up with the motors trying to compensate. You can see in the second plot that it disappeared for a split second, and the drone itself even sounded significantly better.
This may be a characteristic of the frame coupled with insufficient filtering/damping. I will see if I can find some damping silicone plugs to stick i in the motor arms and see if it has any impact.