My therapist mentioned the same thing to me recently so I suppose it is worth investigating further.
I had never considered it before that, probably due to lack of understanding of what ADD/ADHD is (when I was growing up the stereotype was high energy kids bouncing off the walls and unable to sit still and focus in class, whereas I was low energy, introverted, and had always done well in school and work so it was never a thought).
Not saying it’s the case. But if so, that would be an explanation that would make sense to me.