Lots of red flags along the way.
Communication was spotty. Hiring manager seemed tired and distracted in first interview and asked personal questions that should not have been asked. There were gaps between interviews with no communication about what was coming next or if anything was coming next. Except for interview with product manager, no one ever attempted to sell me on the company or the product.
Last pre-offer step was learning and demoing their product back to them. Expectations were unrealistic. Successfully learning and implementing a complex product and then demoing its value in about a week is no easy feat. Post-demo, detailed questions were asked about features that required much deeper learning. They need to rethink their interview process.
I most likely would have declined an offer; was not disappointed when I didn't get one.