This is the best summary I could come up with:

In late July, a couple of startling papers appeared on the arXiv, a repository of pre-peer-review manuscripts on topics in physics and astronomy.

Instead, rumors seem to be flying daily about possible confirmation, confusing and contradictory results, and informed discussions of why this material either should or shouldn’t work.

Apatites are a class of chemicals that form similar crystal structures; this particular version is primarily composed of lead and phosphate groups—all of its constituents are cheap and readily available.

The version developed here, which has been termed LK-99, was made by reacting a lead sulfate with a copper-phosphorus compound (the reaction requires high temperatures for over a day under a vacuum).

The researchers claim the overall volume of the sample drops by about half of a percentage as a result, and that change is accompanied by shifts in the orientation of various atoms and bonds.

Superconductivity is associated with a number of very specific properties, and the researchers measure two of them: the expulsion of magnetic field lines (called the Meissner effect) and the existence of a critical temperature at which conductivity changes.

I’m a bot and I’m open source!

Anyone think there’s a connection between this and the recent UFO spectacle in congress / media?

On top of that, a group made similar claims and produced data and the data was unclear as to whether it was manufactured/faked. Everyone expects this to be fake, so instead of saying “remember the hype last time that was fake” they are saying “you should be so hyped that you can’t prove it is fake and give us money this time”

Everyone who followed it at first is not holding their breath before reproduction of results.

Cold fusion.

https://www.iflscience.com/hopes-dashed-as-lk-99-confirmed-not-to-be-a-room-temperature-superconductor-70165