Allowed 90 minutes for coding challenge. Finished in 12 minutes and passed all test cases. Rejected. What happened?

Company contacted me for a coding challenge for internship. I finished both questions the day I got them in 12 minutes, even though I was given 90 minutes. I passed all test cases (there were about 12

Company contacted me for a coding challenge for internship. I finished both questions the day I got them in 12 minutes, even though I was given 90 minutes. I passed all test cases (there were about 12 per Q), so I was feeling pretty confident. About a week later I get a rejection and am struggling to figure out why. I’ve heard that this company sometimes rejects people for not being a junior, but I am a junior.