Rejection after the final round with hiring manager, is this common?

I recently passed all the technical rounds and met the hiring manager for a final round a few weeks later which I assumed was a culture fit/levelling round which I thought went well but was rejected the next day. I was shocked because I have been in this industry for over 20 years and from my experiences getting to the final manager interview almost 99% means you get the job. Because my assumption was a hiring managers time is so precious they would only talk to a finalist. So has something changed with the hiring process? (OP note: edited to make the timeline more clear, the HM manager meeting was scheduled after the tech rounds)