My experience as well. It's happened a few times now that I'll ask a coworker a question about some system they built, and they tell me to just ask the AI.

I did ask the AI. I gave it several rounds. I got a summary of their diff from it. I skimmed their diff myself. I have a rough mental model of the work they did, plus what the AI did/didn't tell me. I'm asking THEM so THEY can confirm my mental model is correct to the code they supposedly authored.

I suspect the real problem is they vibed the whole thing and didn't even self-review it. So they don't know, can't answer, and the interaction is truly pointless. They are not the expert any longer. It's not worth asking them.