As I understand it, superconductors work best at temperatures approaching absolute zero (-273.15C). For example, Google tells me that the superconductor in an MRI operates at -269C.
There has been a lot a buzz lately about room temperature (25C) superconductors being discovered, but why is room temperature the focus? Why not focus on superconductors that work in reasonably cold environments? For example, we can easily get temperatures to -15C in a freezer. Why not create superconductors that work in that temperature range rather than 25C?
Because then it wouldn’t be easy to implement and won’t work in consumer electronics. The entire point a room temperature superconductor is exciting is because you don’t have to create a special environment for it to work, which immediately makes it a million times more useful than a superconductor that would work when cold.
Still, LK-99 isn’t confirmed to be a superconductor, we’re still waiting on more tests.