I think the vibes refer to the running software, not to the code itself. I hate the whole concept deeply.

The vibes are coming from changing to actual product (design, UX, functionality) and not from the code. The code in fact doesn't matter at all. At this point that's only ok for throwaway prototypes (but for those it's quite wonderful), the more the application requires careful maintainable engineering, you need to read every line and leash the LLM. It's a bit of a continuum between the two edges in reality.