Been said already, but he’s a boy and he’s only 6.
The problem is with the school and the system really. “Targets” mean that the teaching staff have to try to ram as much into them as possible in as short a period of time. Schools with a fairly bright intake can be especially tough because what they get measured on is the improvement on the baseline at the start of the year or key stage. We noticed this when moving away from urban area to slightly posher neck of the woods I.e. The school push a lot harder.
Its sh1t really as the kids who aren’t natural academics are getting turned off to learning at a very early stage. Our 6 year old is really struggling with the transition to year 1 and he isn’t the only one in that year group. Parents requested a meeting to complain about the quantity and level of the homework (spelling test for 6yr old FFS!) and were simply told by the head of key stage 1 “well there’s a lot to get through….”
As others have suggested, you can help by doing things at home that promote focus I.e. Building toys and drawing / painting / craft work.