Canva Front End Engineer interview questions

An online test on HackerRank, after finishing the coding challenge, they sent me an email to inform me that my work was considered not qualified. I was very curious about the reason because the test only contains one algorithm question. And I was pretty sure that my answer should be the best. So, I wrote an email to their recruiter and asked them why I was turned down. I just wanted to know the reason and whether they could give me a better way than my solution if possible. Then, the recruiter replied to my email, and said that they had a plagiarism checker, which means they think I am a cheater and might copy the code somewhere else. At that point, I was so furious and told them that the algorithm question they gave to me is not that difficult at all. In fact, I first met this question on LeetCode. Then, this year, when I was interviewed in Microsoft China, they gave me the same question. So, at least, this question was my third time. I know the best solution, but that means I am a cheater??? So, for those people who would take their coding challenge online, I have suggestions for you guys. Do not try to do an algorithm question in the best way because the great Canva will think that you are a cheater and their successful so called "plagiarism checker" is so smart that it can tell that your code is nothing but rubbish-like copy work. I have never been so angry and disappointed like this before, their arrogant attitude is totally a disaster. I would recommend them not to use this way anymore because the better the code that candidates give, the more likely Canva will think it's plagiarism. Very funny, I write this interview experience just to let everybody know it and be fully prepared if you are going to take such an interesting online test with Canva.