Potentiate interview questions

I had two experiences with Potentiate. Both were unprofessional .. First one was in November 2021. I applied for the senior CX account manager role and was initially interviewed by the hiring manager by phone and then via MS teams. The role was really interesting with their team working with the automotive clients in Australia and I saw my skills being applied in the role with a potential for growth. The third interview was with the hiring manager and another team member which also went well. Then the HR person reached out and advised me that they will try to set up a meeting with the head of research which will be the final round unless theres a final task required. There was a gap of 2-3 weeks where the HR or the hiring manager did not reply at all. I kept waiting for the final round interview as advised and declined couple of other offers as I was really interested in the role. After 3-4 weeks, I followed up with the hiring manager again and was advised that they already recruited someone in the past month while keeping me waiting for the last round of interview. I started a 6 months contract with another firm and once it ended, Potentiate was one of the companies I checked again if they had any roles. I connected with one of the hiring managers who had an initial phone call with me followed by two meetings with MS teams, and another call from the hiring manager asking as a follow up. There was a question about salary and I told him I was OK to negotiate because I am really interested in the role. A week or so later, I got a call from their new HR manager and I was advised to stay put as the next interview will be with their head of research. Then there was a gap of another month and I kept following up with the hiring manager on the progress as I felt that both the hiring manager and I connected well and we were on the same page with regards to the role, the requirements and how my skills would add value. A month later, history repeated itself. I got a mail from the HR that they had already recruited someone. This is when they kept me waiting for the final round interview with their head of research again. What's worse, they forwarded me some other candidate's email chain where they are corresponding to setting up appointments and follow-ups for their last round of interviews, and tacked on a response to me on top of that saying that my interview process will not be progressing further. A found the whole process to be a bit unprofessional when after completing 2-3 rounds of interviews, advising me that my next interview is with their head of research and they will come back to me with the dates, then there is complete silence for 3-4 weeks and after following up with them multiple times, I would get a response saying they will not be progressing with me. Why keep me waiting for weeks saying they will schedule my interview with their head of research, when they did not want to progress with me? Very unprofessional!