Insight M Senior Software Engineer interview questions

An hour call with the staffer (they actually ghosted me on our first scheduled call and had to reschedule), then a beefy take-home coding challenge followed by five separate one-hour sessions with team members, manager, and CTO. Sessions included behavioral, background, and a few technical questions. One session was to go over the take home challenge answer. After passing the take-home challenge (which I believe is accidentally set up in a way that it is impossible to fully complete - more below) I was immediately scheduled for the five sessions and completed them all. The entire time I felt like things were going really well. Conversation flowed smoothly and I was getting on great with folks (smiles, laughs, nods). They seemed happy with my answers. My ten year background in scientific and back end computing was a wonderful fit for this role. Despite all that I was rejected with zero feedback. All told I probably put 20 unpaid hours into this process and did a great job. I highly resent receiving no feedback whatsoever. It was insulting and demoralizing. Also they don't mention in their job description that there is an on-call component to this role. They said the weekly on-call is shared among ~13 staff so you won't be on call often. But one of them let slip that actually the number of staff who are responsible for on call will be reduced so a smaller number of staff (including this role) would carry a higher load while the others are freed to work on other stuff. Staff mentioned having to work all day on the weekend or be up at 10pm. This is due to a fragile data pipeline that needs to be babysat.