Honestly, at this point I stopped making strong conclusions about candidates based on a single interview. I won't recommend to hire but also won't judge their abilities overall. Interviews can be very stressful, candidates overthink and often get fixated on a random solution they think the interviewer expects, etc.

I had several odd experiences myself in the past, as a candidate. The funniest one was when I interviewed at a prestigious company I thought was hiring only top talent. I spent an hour trying to come up with the most efficient Sudoku solver, got completely stuck on some arbitrary algorithm that I came up with on the spot. It wasn't a "circle pattern" but close to that. Wanted to impress the interviewer and also did not sleep the night before overthinking the process.