Not the OP, but after a couple of decades of people pointedly talking about eye contact, small talk, and body language, you learn “coping mechanisms” to deal with neurotypicals and make them more comfortable.

Did your sporting team have success on the weekend? Wonderful, direct eye contact, smile, mirror. Ok, now, to business:

Commonly called masking - learning the 'rules of the road' for peopling - the hardest thing that young folks with autism or ADHD need to learn is that you must learn how to do this, the world will not (often or always) change to accommodate you - but once you do it, you can appear more or less normal most of the time.

There's nothing in the diagnostic models for nearly any mental health concern that presumes a patient would forever earn that diagnosis nor (certainly) that its presentation would be identical through their life even if the diagnosis stood.

There are some clinicians and unfortunately now many patients and caregivers that nonetheless take an essentialist view of diagnosis and come to identify their patient/self/child/peer with what's really just meant to be a guideline for support with ongoing dysfunctions.

In reality, most people face some fluctuating bag of dysfunctions over the course of their life, with fluctuating intensity, with contributing causes too diffuse and numerous to identify. They might be diagnosed squarely by one clinician with one thing thing at one time, then see some other clinician the same day who thinks the diagnosis was overstated or preposterous. Or they might find that a qualifying symptom that seemed very salient at one time of their life hasn't been an issue for them for a long time because of some new learned behavior, some change of circumstance, etc. Likewise, they may even find themselves facing new or greater dysfunctions compared to what they'd experienced or noticed before, precipitated through known or unknown reasons.

For people most intensely disabled by mental health dysfunction, they often can't escape that dysfunction entirely without the discovery and resolution of some kind of radical physiological or environmental issue.

But for the majority of people who just found that they had a hard time with their daily life, but were otherwise independent, and received a diagnosis that helped them see some constellation of related factors and opportunities for accommodation or treatment, things are hardly so static.

For most of early psychology, this marked the distinction between "psychotic" and "neurotic" presentations. The former represented a disruption so severe that escaping disability and achieving independence were largely out of reach, whereas the latter were understood to be real but fluctuating or even ephemeral disturbances.

It's not really until very recently, when so many people started to obsess with "identifying" themselves with this thing or that thing in some kind of permanent way, that this distinction began to fall out of mind.

In the case of those diagnosed with autism as part of generally independent and functional lives, it's not hard to find people who have experienced changes to the symptoms that originally qualified them for the diagnosis -- sometimes positively, sometimes negatively; sometimes during certain times, sometimes permanently. It's also not hard to find people who received such a diagnosis at one time and either felt comfortable fully rejecting that diagnosis at some later time or had a clinician who strongly questioned it or refused to confirm it. None of this stuff is static and much of it is subjective.