Kasalis interview questions

A phone screening with HR, followed by another with the hiring manager. I was then given a take home exercise and brought onsite for 3.5 hours of interviews with multiple members of the team. I had a good experience during the process, but after my onsite, I was ghosted. They never got back to me to tell me I didn't get the job, even after I followed up. This is very unprofessional behavior. I dedicated a lot of time to this interview process and I would have appreciated the courtesy of a response.