I've never heard about that and I'm pretty sure it's incorrect (although "machine learning" is a wide term), do you have a source for that?

I've also never heard this before. The closest I can think of is fuzzing test suites used to find panics in various crates, but that's neither machine learning nor in the compiler itself.

I know that datalog is used for the borrow checking logic, so I could also maybe imagine someone describing something like that in some hand wavy way like "proof by machine to detect up front whether the program is safe or might crash" and that getting misinterpreted, but that seems like a stretch