high intelligence can and will make it harder to detect learning difficulties & mask life struggles. Because despite the genetic learning disadvantage of adhd/autism, things get averaged out by being smart. You can also find coping strategies easier and just figure things out on your own

also adhd evaluations always look for signs during childhood, and if you are smart enough of a kid you won't struggle in school despite not being able to focus on regular learning like everyone else - the consistency of symptoms is pretty much half the diagnosis and having those symptoms be invisible to everyone but you complicates things

most tests (apart from self evalutations) don't really test for things like regular life struggles, and if you only recently started being able to see your symptoms (that were previously masked by high intelligence, and only now you realised something was off about it all) it could lead psychologists/psychiatrists to belive it's something else - like anxiety or depression (both of which can also be caused by adhd so that makes stuff even more annoying)

if the sentence "oh you have so much potential, if only you applied yourself" has been repeated in your childhood as if on a loop, and now makes you want to cry and/or smash things, you're probably like me - and the above is how my diagnosis went