Segovia interview questions

A recruitment agent reached out to me with the job spec and started the process. The role seemed a promising one and the package was above market rate. The initial screening call lasted for around an hour. It was to get to know each other and check basic tech skills. As the second stage, a take-home exercise was given. It was a simple API integration task and developing the client code. It took about 5 hrs. There was another one-hour session to discuss the take-home test and ask questions around that. Another one hour session to discuss with the product and delivery team members. I spent about 10hrs on the whole process. After passing me through all the stages to the last stage (an interview with the product + delivery), they said it's a NO. The company didn't even bother to give me why it's a no even I requested. So I am totally in the dark. Moreover, I have reached out to one of my ex-colleagues and got to know this company did the same to him too. No feedback after all the rounds of interviews. Also, I suspect if those roles are genuine, they put a high salary and silently disappear if you ask for a feedback. This is the worst interviewing experience that I had in my 10+ year career and will NEVER recommend this company unless if you want to waste your time and effort. Stay away!