I interviewed for this position while I was laid off. So, I ignored some of my own rules when applying to positions. One of the top rules being, don't do any work for free.
The interview process started off basic enough. Actually, it seemed better (shorter) than most. Screening call with the recruiter, then an interview with the hiring manager. Both of those seemed to go great. However, the third 'interview' was a presentation they wanted me to prepare. Normally, I would refuse to move forward in the process as this is free labor, but I really liked the company and the mission. Also, I was unemployed and didn't think I could pass this opportunity up.
They gave me access to their staging site (red flag 1), and had some prompts they wanted me to follow. They were asking me to solution and roadmap for real company problems, and not made-up scenarios (red flag 2). Anyways, to make a long story short, I put about 20 hours into this presentation. Really wanted to prove myself. The presentation seemed to go well enough. However, everyone on the call, right off the start, seemed disinterested (red flag 3). They recorded the presentation, but I didn't think anything of it as they recorded all the interviews.
Long story short, they ghosted me after this. All I can conclude is they stole my work, and everyone else's, and just used it to fill their backlog and build their roadmap piecing everyone's ideas together without actually hiring anyone. So, here is a friendly reminder to NEVER do work for free. Or, at least get an NDA signed beforehand.