Again with odd or bad electric on reddit. Yawn. Boring.
It's not dangerous. Many consumer electronics use ungrounded, unisolated power supplies and leak AC current on the DC output. It is very low current, and won't harm you beyond feeling it on some devices. You can actually measure it if you have a multimeter. You'll see something like 60-80V AC, which sounds high, but then if you measure the current you'll see a few dozen microamps.
For reference, a dangerous level of AC current starts around 1mA, so you'll be about 20-1000 times smaller than that.
If you're the DIY type, you can make a little filter adapter for your power supply. Plug the power supply in, the filter uses a capacitor and resistor to connect to ground, which will remove most of the AC voltage, and then you just output to your laptop. You won't be dealing with AC mains, so it is pretty safe. Alternatively, just buy a new plug online. However, be warned that even some 3-pronged adapters leak AC current, so just being 3-pronged isn't a guarantee. Your best bet would be buying from a good manufacturer.
You won't have any recourse with contacting the manufacturer of your laptop. There's noting actually wrong with the power supply.