[matheweis]

Wasn’t LK-99 a copper doped lead apatite? Is this different?

[sanxiyn]

This is a derivative, with slightly different chemical formula (namely, this includes sulfur, while LK-99 didn't).

[kuschku]

Though the original, supposedly superconducting LK-99 sample, was produced in a way that caused it to be contaminated with sulfur. So this might be why their sample acted the way it did.