Agile Actors Software Developer interview questions

First interview with HR discussed remote options and agreed that the company is flexible, discussed the compensation and benefits and they said ok. Then received a home assignment which as I understood its real work for free. Eventhough I ve done it, and moved to the technical interview. Discussed about my decissions on the Design and implementation and other than a couple of mehtods naming, they didnt find anything else. In fact they said they were impressed. I assume I will get an offer but next day they called from HR and said "we wont move forward". When asked they said the technical interview's feedback was positive but did not justified where I lost points. Going back now and thinking of it I feel robbed. And there are many companies like this one that launch hiring campainges when having bottlenecks in their projects. Also the feeling I got from their Senior Devs was that they dont have depth in their knowledge