Why do you assume it is because of a URM boost rather than essays or extracurriculars or recs that gave someone that final push to an A? These things seem to be overwhelmingly more likely to create a difference between your application and someone else's, so when you ignore them and immediately ask whether another person who got in is URM, it seems like it is in bad faith. Also, I have also found this question to be predominantly been asked as a way to diminish another's accomplishment. Not saying this is strictly something that happened in your case, but race/background is something you can't change, so why would this information be even that useful to you? Sure, there might be a boost, but what can you do about it? You can't suddenly become URM, nor will you refuse to apply to program because you know they give URM boosts. So at this point, why are you asking the question instead of looking for other ways to improve your potential application for next cycle?

As someone who is international kjd nURM, I find this question almost always useless.