I suppose, if you want to be pedantic about it, ever thing is impermanent, but talking specifically about art; there are certain art forms whose temporary nature is an integral part of what they are.
I’m talking here about, for example, performance art, once the ‘performance’ is finished, the art ceases to be, until the next performance, and then its not the same performance as it was, it’s not even an exact replica of the original. that would be impossible.
Performance art