This thing is an absolute beast of a theorem, notorious for its size, and well worth verifying even if the verification is bad (as one would assume it is). It is an amazing achievement that the thing is apparently completely correct.
The largest math proof in human history is now computer-verified.
Today, Axiom announces a complete Lean auto-formalization of the Classification of Finite Simple Groups, the "periodic table of symmetry."
About 15,000 pages, built by over 100 mathematicians across generations.