Ok from what i understand, this paper is proposing that a very specific substitution of the Copper atom in the place of the lead atom in the lead apatite structure is responsible for this
This only happens at a very specific atomic site but it alters the structure of the material in a way that creates a "Flat Electronic Band" that is key to Supercon
But since it has to be at that very specific site at a very specific atomic proportion it could explain why people are having trouble replicating this material exactly
https://arxiv.org/abs/2307.16892
https://nitter.net/iris_igb/status/1685731177523449856 I think this twitter user did see the meissner effect as well, I'm not well-versed enough in chem to really know what she did here, especially since she says it's not a replication thread, but she appears to have been messing with a production method of the material and did see strong diamagnetism?