I went through 8 rounds of interviews, yes, 8. After meeting with the Director of Recruiting and their boss and another HR person and a senior stakeholder, the hiring manager then kept adding additional interviews, about every other week, promising each time that this was the last round, only to then add another interview.
The process took over 2 months. Some of the interviewers seemed to have no idea why they had been asked to interview me or what the role was that I was interviewing for.
Then suddenly one day the hiring manager cancelled the remaining interviews and after several more weeks of ghosting, they told me they had decided to hire a contractor instead.
One of the interviewers also asked me to do some (unpaid) work for them, editing and adapting a job description for the company. So overall this was a terrible experience.