First of all, complaining about minorities getting lower grades because their English is not as sophisticated as that of others is the inversion of the idea of teaching. That feedback is actually great. We have machines that can give that feedback (e.g., grammarly)? Then use it to make everyone's writing better. Grades are just a measure of the success of learning, after all. I never got why one would not allow a student to repeat a particular test as often as they like, tbh.
Second, grading essays this way is a clear violation of the idea of teaching. What do you want the students to learn? Structure? Knowledge transfer? Grammar? Writing an essay is such a complex task it is a really too broad goal. And then naturally grading becomes quite difficult.