What are the most common mistakes in system design interviews?

i've done about 15 mock system design interviews recently, and the feedback feels a bit inconsistent, but some common themes are emerging. i'm trying to identify the most frequent mistakes that candidates make. for instance, sometimes i dive too deep into a specific component too early, other times i stay too high-level. not asking clarifying questions upfront is another one. what are the most common pitfalls you observe in system design interviews, especially from an interviewer's perspective? what are the classic anti-patterns that often lead to a 'no hire'?