We Are Builders interview questions

Was contacted by them for an open Front End Developer position. The job description did not require any previous back end experience. I first had a video call with one of the co-founders. Really nice guy, discussed a bit about their projects and my background. Things went smoothly and I was given an assignment: a small project that replicates basic functionality of one of their start-ups. On the assignment's page there was a final step mentioning that I will have to present my work to the team. Prepared for that but got asked to send the code as it is or make a video if I want to add context. I found that a bit odd. I got an email back from them saying that they were impressed with the outcome of the assignment and they want to schedule a final interview with the other co-founder to discuss about the open position, again, as a front end developer. Scheduled a call and was prepared to further discuss the details of the job. The call was a really strange experience. It started with me being asked to present what I've done for the assignment again, then being told that the position is remote (they never told me anything about this before) and that he thinks I am a junior-to-mid Full Stack Developer (I applied for the Front End Developer role). Without being able to ask for some clarification, the co-founder told me that he will be back with an answer soon. I got an email two days later from them saying that I am missing backend skills (again, after being told by the co-founder that he thinks I am a junior-to-mid full stack developer) and that they will not continue with my application. It was a weird experience and I think I dodged a bullet.