Switch power supply that whistles

Not too normal.
When you talk about a switch, I think it's a network switch.
But we need to know the type of buzzing and the type of power supply. Is it a transformer? (heavy)
And when it's not under load (with nothing plugged into it), far away from anything else, is the buzzing the same?

As a precaution, I would advise you to change it quickly. In any case, it's not repairable. This thing is sealed. You'll therefore always have this noise.

A power supply in poor condition can burn out. The smoke is very toxic then. Just because it makes noise doesn’t mean it will burn out. But in the meantime, don’t leave it plugged in unattended.
(By the way, you should never leave power supplies plugged in unattended).

Yes, it is indeed a network switch,
an Olitec 5-port Ethernet with a transformer.
I haven't tried it empty yet. I'll test it tonight and let you know what I find out tomorrow.

Is it possible to exchange it in the store? Because I bought it about 15 days ago... and it would bother me to buy a new one.

Could it be a manufacturing defect? Because I bought it new and I don't think it's low quality (paid €30)

Alright. But don't worry, my power strip has a power-off button and I always turn it off when I'm not at home for safety.

yes that's true...

no 30 € but it's true that it's still not cheap for a 5 port switch.

I'll test it without load and if the buzzing persists, I'll turn to customer service.

We'll see...

to be continued...

thanks for your advice cafecho

And does it whistle more on your mom's bike? So it's an incompatibility between the switch and the transformer then.
What a crazy story!
Check that the maximum absorbed power of your transformer is sufficient for the bike. (in VA) If it’s not enough, it will overheat.
(for the bike's transformer on the switch, the power should be fine, a switch consumes little)