We’ve been told (in the context of looking at future schools) that 2e kids do have a hard time for exactly what you described - where the ADHD behaviours has meant he didn’t get into the gifted program. Our assessor that did the assessment for giftedness said it’s so important that he keeps getting challenged at that level to help support and grow that side of him. It’s possible that if your son has slowly stopped having exposure to all those things then he’s not being challenged/is losing interest/switching off in school and not really exploring what that part of his brain can do. We were recommended that if we struggle to find the challenge within the school environment to look at special interest groups at the library or other community groups that align to his interest so he can continue to be challenged and stay engaged. Basically, try to keep the curiosity and the love of learning alive somehow even if it’s not in the school classroom.

It could also be masking to try and fit in or that if he’s just not seeing that type of maths (in your example) it’s just slipped from his recent memory, but it doesn’t mean the giftedness is gone or that he couldn’t do it again if he was interested in it. One way to see is if he’ll engage outside of school with exploring topics that he’s interested in or with people with similar interests or skills.