The knob you choose to play with seems normal. It will turn normally, if you decide to do so. It will turn little flames on if you turn it counterclockwise slowly enough, but nothing will happen if you twist it the other way. It’s a normal working stove knob.

The other knob next to it, though, looks different. It has a sort of sparkly sheen to it, as if the black painted over it is new and doesn’t fully cover its real color. If you choose to twist that one, it is wiggly. And if you twist it hard enough, it will come loose in your hand.

But try all the knobs just to be safe, if you want. But that one is odd, and it’s clearly going to be noticeable to you.