A jury is not required to explain the reasons for their verdict. In many, probably most, cases the judge won't be able to tell that the jury convicted for improper reasons.
Many apparently don't; there are lots of examples of defendants of colour getting convicted in cases where white defendants get acquitted or receive a very light sentence.
Are the cases the same, or just the charges? Why did the defendant choose a jury trial as opposed to a bench trial if they believed the jury was going to be racist? What was the racial composition of the jury in both cases?
The story is usually a lot more complicated.
There also reverse cases of this too, because high-profile cases are usually dealt with more severely, not because of race. For example, a cop in Florida killed a 36 year old white man in very similar circumstances to George Floyd, and got off scot-free. So for better or worse, notoriety also comes into play.
