https://techcrunch.com/2023/08/18/lk-99-room-temperature-superconductor/

If there was any hope remaining that LK-99 might be a room-temperature superconductor, it’s pretty much dead now.

In fact, it’s worse than that. Pure samples of the substance show that it is an insulator — the opposite of a superconductor. The glimmers of hope that kept the story in the news for weeks appear to be the result of impurities in the original samples.