I apologize if this is not helpful. Also, we live in a high achieving district that claims to "get" gt kids and differentiates for them. (Our ds was tested privately last year- hg with vision issue)
I have had a similar experience with the school telling me my ds6 "has a peer group" and "some are achieving more than him". Ok. There is nothing I can say, really. (He doesn't like writing, has vision issues and is going to VT, and hates math fluency.) In comparing within the box, his output is not as great; BUT he has the knowledge and know how.
My ds similarly "acts" fine at school. Home life (before/ after school) is quite different. We believe he is holding it together at school and letting his frustrations out at home. He does have a pleaser type personality. I also think he realizes he is different from his classmates. (Btw, this year is slightly better than last year. Nice teacher. More flexible teaching style.) At this point, we are questioning whether this school "gets" our ds, and if they will service him at all.
You know your dc. If he is acting different at home. Something is going on. Trying to get the school to help may be more challenging. Maybe getting some testing might help you figure out what is going on.