Except all that still assumes that his *9V* supply was greater than 10V...
More likely... counterfiet parts of junk quality and the 3.3V is shorted internally. The only other part in between is the little chip capacitor (or the artwork.)
If I didn't write it already, the open-circuit voltage on the power adapter is 13.7 volts (on a DMM).
The fact that there are two datasheets for what may or may not be the same product simply means one should use another manufacturer. There is an opportunity here to design a good quality substitute for the power supply and then sell it on the web. That one YwRobot supply is sold by MANY vendors. Think how many one can sell as its competitor.