I have to conduct a lot of coding interviews at my job (I personally think DS&A interviews are kind of stupid, but I get assigned to do them all the time anyway). I recently did one with a senior engineer who seemed like he was sort of blowing off the whole thing, and also forgot almost everything about the language we were running it in. In my feedback, I noted that it was one of the worst DS&A interviews I've ever done, in that everything was a fail on our rubric, but also he seemed more or less competent to me based on our conversation.

In the interview debrief, one of our managers also stated (in response to my feedback) he doesn't really care about DS&A interviews. And then the hiring manager completely ignored the bad interview feedback because it turned out the candidate was a referral and everyone already knew he could code. So the whole thing (at least the whole coding interview thing) was a waste of time, since literally nobody involved seemed to care what happened in the interview, including me, but I guess if there's an interview process everyone feels compelled to follow it