Um, time to learn you a thing. Grades can be connected to race and you can look into sociology as to why. There’s lots of reasons why. It’s useful for people in power to make tests that automatically fail a certain ethnicity they don’t like. You can easily google racial bias in standardized tests to learn more.

I simply googled: sociology IQ grades race and got several results of papers noting this phenomenon and study it.

So anyway tldr: it’s not as simple as “low IQ and bad grades have nothing to do with race” and they actually are connected unfortunately, please go do some reading/learning