Otherwise I have to write it's just a vent hole or release catch for the maker to open it up. If you feel like it's a spy cam, just put the usual black tape over it or destroy it. USB chargers here are cheap, plentiful.
There is a cell phone charger where the there is a tiny hole at the USB part that plugs to the outlet piece. The hole resembles a tiny spy cam (not assuming, just describing) and right under the hole is what looks like a very small qr code or something. What is that and what is it's purpose? It's on the plastic part by the way and it's an all white cord that was plugged in to a non-matching outlet piece.