USB-C Docking station creates static noise whenever I move my mouse (which isn't connected to it)

I recently purchased a TARGUS USB-C Docking station with PD passthrough. I have connected a VGA monitor to it, as well as using it for passthrough power to the laptop. My mouse is connected to a USB port on the laptop (Latitude 5510). Whenever I move my mouse, either using the attached USB mouse or the trackpad, the docking station makes a static noise, a bit like a modem. If I remove the passthrough power, the noise stops - but I don't see the connection between moving the mouse and the PD passthrough. I presume there's some kind of hardware fault / feedback loop going on? I've tried plugging

Question by simonalexander2005 on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.