Unfortunately, the entire process demonstrated a lack of professionalism and respect for my time and efforts.
Firstly, in all three interview rounds, the interviewers were consistently late. In the first round, I was even falsely accused of not showing up on time, despite being present the entire time. It was only later that I discovered this appears to be a recurring issue with them.
The behavior of your CTO, N, during the later stages of the interview was nothing short of obnoxious. Instead of fostering a collaborative and professional discussion, he seemed more interested in stepping over me and trashing my past experience, which appeared to be a deliberate attempt to create leverage for negotiations. Furthermore, it was evident that he lacked both subject matter expertise and a basic understanding of programming, which made the experience incredibly frustrating and unproductive.
If you are not desperate for the job, RUN!