Nothing of great interest. That's a tiny scratch in the surface of the planet, less than 1% of the radius.
On the other hand although we lack the technology you'd need to destroy the damp rock where we live, we only live on some dry-ish outside surface parts of the rock, and we could trash that part and drive ourselves extinct. "Oops"
They were asking why the two deepest holes, despite being nowhere near each other, dug decades apart, are 99.3% of 12km and 99.5% of 12km respectively. Was BP symbolically honoring the russian scientists? Does the earth have an extremely uniform material property that happens to be at a very round number of km? Just a complete coincidence all around?
(I asked AI, and it says coincidence, since BP stopped drilling once they hit oil, and the russians stopped drilling once they hit some melty rock.)