Portrait interview questions

They asked me for a "Spec Work" during the interview. Review their product, offer suggestions, analyse opportunites. Even asked to make a prototype and write a PRD. That's unreal! There is a clear opportunity to use these interviews to cut down product management costs by obtaining candidates' work for free. Funny thing is that they always made it look like I was a good fit until I handed in and explained my work to them. Thankfully, since I already suspected it could be a "fake" recruitment process, I didn't spend much time on the assignment. Just being clear, I don't have any proof of their malicious intent. I'm just pointing out the evidence here in case someone wants to know more about Portrait's recruitment process. To whom it may concern, salary ranges were below average for the US, and they were targeting remote candidates.