On the more compelling side, we have a video reportedly from a research group that synthesized some LK-99 (it appears to be from the people who posted this report) and showed that it rejects magnetic fields strongly enough to levitate away from them—a hallmark of the Meissner effect. With a strong enough magnet, it’s possible to get nearly anything to levitate (including, apparently, mice), but this is done with not especially strong magnets, and clearly at room temperature. And the small chunk of material isn’t lifted evenly, consistent with only a small crystal within the sample actually superconducting.

On the less compelling side, a different group has apparently synthesized the material but only finds that it superconducts up to about 110 K—nowhere near room temperature. Whatever was made here also doesn’t seem to have a critical temperature, instead seeing a gradual increase in resistance above that point, and the Meissner effect tests came up negative. That’s pretty inconsistent with the original results and suggests that what they have isn’t a typical superconductor at all.