There are two pins. One has 225V to ground, the other one has 230V to ground. So the voltage from pin to pin is still 230V-225V = 5V.

Yes, and given that USB devices usually don’t have protective grounding (since they expect to be supplied 5V to ground at most!), you just might be what eventually provides that ground connection when you touch a conducting part of the case…

Surely this is a violation of the specifications?

Definitely at least electrical standards in most countries, and probably USB also specifies that the voltage needs to be isolated from mains.

But yeah, usually those are illegal to be sold.