Honestly my experience from using AI to code (primarily claude sonnet) is that that "extra 47%" is probably itself mostly tech debt. Places where the AI repeated itself instead of using a loop. Places where the AI wrote tests that don't actually test anything. Places where the AI failed to produce a simple abstraction and instead just kept doing the same thing by hand. Etc.

AI isn't very good at being concise, in my experience. To the point of producing worse code. Which is a strange change from humans who might just have a habit of being too concise, but not by the same degree.