Questions about USB quick chargers, and buzzing sounds

First: I just noticed a very faint buzzing, even a little clicking on my Samsung quick charger. I have to get close to hear it so I’m not sure how long it’s been going on. Search pulls up a lot, but what is different from other posts is that the sound stops when something is plugged in and other people seem to have the opposite issue.

Also: I know Qualcomm made the technology and multiple companies adopted it, does this mean I don’t have to buy a Samsung branded charger? And is there an easy way to tell which of the 5 or 6 generations without searching model numbers?

Almost all “switching” power supplies make noise.
The transformers which are used to step down the AC line voltage to DC constrict slightly as they are turned on and off. This generates the buzzing and clicking you are hearing.