A lengthy unpaid assignment followed by numerous interviews. They didn't like my solution even though it solved the issue, and didn't show any sign of comprehension when I took a few days off to work on that task, such as balancing with questions. I was explaining when they (the two) interrupted me to stop the process. They were chatting on google meet. And that was it. They carried themselves in a very unprofessional manner. Don't work on assignments for even five minutes. They must start realising that hiring someone will involve risk.