I always thought the high pitch noise was normal
until i found my spare wall chargers that dont make any noise.

yes they are all OEM chargers. I have had 2 OEM chargers that make noise when charging.

Those are switching power supplies and the noise is the switching frequency or a sub-harmonic of it. Probably just a little piece of metal that has come lose and is being excited by the switching currents and is rattling against the case. Really nothing to be concerned about.

Switching power supplies are great. Not only are they much lighter and more efficient, they usually operate over the US and European voltage and frequency ranges so you can go to Europe, plug them in, and be ready to go without converters or flipping any switches. Everything I currently take to Europe has a switching charger/power supply (including my electric shaver). The only special consideration is the difference in AC plugs which does require an inexpensive adapter.