OpenAI have proven that matrix multiplication can be done in O(n^2.25) operations, which is a massive improvement. It is especially concerning because these AIs themselves run on matrix algebra.
The previous record was O(n^2.37), which had barely moved from O(n^2.4) in 1990.
OpenAI blew it away.
But... it is a nonconstructive proof. No algorithm was found, only a proof that it must exist.