Scalable Capital Java/Kotlin Engineer interview questions

First interview was very friendly and I had a good impression. After that I did a coding task and after one week I was rejected without explainig why. When I asked about feedback I was told that it's not possible. I think that I wrote not such a bad code and I would have liked to discuss it in a technical interview, but there was no such opportunity. I feel very uncomfortable for wasting 4 hours of my time for nothing. I read the reviews on Glassdoor and saw that I was not the only one. I think scalable capital needs to rethink the interview process.