USB-C Power Supply Pushes Almost 2 KW
hackaday.com
hackaday.com
The only real concern is arcing while making or breaking a connection, and the 48V mode has special provisions to avoid that, including the cable having to have provisions to make the the control pins are disconnected before the power pins to give the power supply time to lower the voltage.
Two of my laptops give me a physical 'buzz' sensation when charging via USB-C. Is this because they're not grounded? Should I be worried about the issue at higher wattages?
For EMI reasons, there needs to be a connection (via a very small capacitor) to the primary side. This creates a measurable, and as you've noticed sometimes even physically detectable, voltage leak from the primary side, but is completely harmless since it can't actually sustain any meaningful current.
More details here: https://electronics.stackexchange.com/a/216967/23924
If it really bothers you, you can get a three-prong USB-C power adapter. These can just ground the EMI to protective earth, and you won't feel anything.
You can convert most Apple laptop power supplies into one by using a properly grounded cable, for example; they have a grounding connector (which is not connected to anything using the regular duck head adapters, though – hence the phenomenon of "buzzing MacBooks").
The phenomenon of being able to sense it using your fingers is called "electrovibration" and is actually quite fascinating. There's research into being able to use it as a form of haptic UI feedback!
there are major bugs in both computer firmwares and usbC hubs where special "safety cutoffs" are being triggered in devices so you need to power cycle hubs (not just computer) sometimes, sometimes computers will freeze during boot sequence because of a usb-pd glitch (no mention that manufacturers even care about these bugs in their bios release notes)