Parents with black or mixed boy

I sincerely apologize for how this is going to sound. Mostly requesting advice from other moms raising mixed or black boys. Have you had the chance to speak to your son about racism? If yes at what age? The reason I'm asking is that I had an uncomfortable conversation with my son's teacher which has me wondering if I need to speak to my son about racism. My son goes to a predominantly white school. He's the only black child in his classroom. He's 6 years old and currently in grade one. I've noticed lately that he seems to want to copy certain behaviors that other boys in his classroom are doing. I've explained to him multiple times that he wants to be his own person and not copy other kids especially when they seem to misbehave because he might get more in trouble compared to them. He also started to question why is he black and why are his classmates and all his friends white that shocked me because I've never diffriciante skin tone and had that conversation with him. Questioning if I should and how I should have this conversation with him or is it not important. The reason it's that I spoke to his teacher for a parents meeting. They explained that he's a very smart child, progress well but the only issue is he seems to have more energy and seems to be louder then most kids in the classrooms. She did also asked me if I've checked with his doctor to see what they say about it she later on say that she's concerned because in her years of experience she notices that black boys are mostly targeted in school so she doesn't want that behavior to get worse and they don't see his potential. The conversation was a bit overwhelming because I keep thinking to myself if he wasn't black how would this conversation of went? What exactly is she trying to say? I am very aware of racism still happening but didn't except that my 6-year-old would already face it because seems like that's what she's telling me or am I overthinking this situation?