As a bit of anecdata, I used an LLM to refactor a core part of one of my site projects about 6 months or so ago.

I don't really remember how it works, probably because I didn't have to think hard about the design, I just sort of iterated it in conversation which probably meant it didn't stick.

While the iteration part was mostly positive, I don't know that it was worth it in the end to be left with something that I can understand but feels a bit foreign at the same time.