Remember Heartbleed in OpenSSL? That long predated LLMs, but same story: some bozo forgot how long something should/could be, and no one else bothered to check either.
I believe that once the OpenBSD team started cleaning up some of the other gross coding style stuff as part of their fork into LibreSSL that even fairly simplistic static analysis tools could spot the underlying bugs that caused heartbleed.
Hey we are the bozos