It’s inherent to all class 2 PSUs (or really all PSUs without mandatory safety grounding, which is only safely possible as a class 2).
It happens even in a properly wired building without faults, since a class 2 PSU needs a path for EMI on the secondary side to be dissipated, and due to the lack of a dedicated ground, the only choice is to connect both phase and return to the secondary circuit via a Y capacitor.
A common downside of that is a stray voltage of up to half your mains voltage on any conducting surface of your device, but it’s harmless since it’s not capable of sustaining any meaningful current.
It happens even in a properly wired building without faults, since a class 2 PSU needs a path for EMI on the secondary side to be dissipated, and due to the lack of a dedicated ground, the only choice is to connect both phase and return to the secondary circuit via a Y capacitor.
A common downside of that is a stray voltage of up to half your mains voltage on any conducting surface of your device, but it’s harmless since it’s not capable of sustaining any meaningful current.