James Hawkins, after being on a team that’s interviewed over 725 people:

It’s normal for candidates not to ask harder questions about our company, so they usually miss out on a chance to (i) de-risk our company’s performance and (ii) to increase the chances they’ll like working here.

Does the company have product-market fit? How much runway does the company have? Does their spending look within reason? What’s the culture like? And more tough questions that you really should be asking before accepting that offer.