One interesting theory here is contamination. "Legitimate" labs have a higher standard of cleanness and material purity, more stable equipment etc.

If the results are to be believed the crystaline structure is hard to achieve as replacing the right parts with Cu seems borderline random.

less perfect synthesis materials (some of the unofficial institutions have even admitted to using subsitutes for some of the synthesis) so perhaps worse ovens that cannot sustain perfect temps, or substitute materials in some way help the right crystals to show up.

The original Korean lab said they only had a 10% success rate and admit the ppublished synthesis is incomplete because it is waiting full journal approval for the paper to come out.

So we should wait until we have better data, better replication and tbh a working theory of how it even works because it shows odd magnetic behaviour, whether its superconducting or not