Sifted interview questions

I was asked a few initial questions on the phone, went great, and the chat was followed by a written coding exercise for which I was given a few days. I sent back the exercise with my (fully tested and documented) code and got feedback that it wasn't good enough and they would go on with other candidates, which surprised me a lot since my code was clean and perfectly working. I assumed they expected more comments, different styling or maybe I had misunderstood the requirements, so I said I understood and asked for some details on the feedback so that I could improve myself for other applications to other companies, since I couldn't see anything obviously wrong with my code. They said they would check with the engineer who reviewed my code but never got back to me. I chased once 2 weeks later, never got a reply. At that point I strongly suspect the task I had to complete was actually a task that was needed on their end and which they gave as a "coding exercise", for which they probably never even intended to hire someone. So basically I worked for free. I can't prove it but even if I'm wrong, ignoring the candidate by not providing feedback is already an issue.

The allow you to be yourself and are honest they dont try to sugar coat things what you see is what you get both managers are people you want to work hard for