It's fantastic that you're seeking clarification while providing unwarranted support for your child. ADHD's difficulties with working memory and focus can undoubtedly affect retention, even in children who excel academically. Anxiety, learning gaps (from previous transitions or online learning), poor sleep, or even certain learning disorders like dysgraphia or dyscalculia that can coexist with giftedness should all be taken into account if the ADHD diagnosis seems dubious.
For a closer look, have you thought about getting a neuropsychological evaluation? It could confirm
ADHD or reveal any unidentified problems. Additionally, executive functioning coaching may aid in the development of abilities such as procrastination reduction and retention. Would your child be willing to investigate that?