I don't think that the author has ADHD, because they used to be more attentive in the past. In the case of ADHD, it was also the case as a child.

I also got the diagnosis of ADHD (inattentive type) a few months ago, in the interviews they asked whether I also had these symptoms as a child. Not easy to figure out because as a child things like finishing things on time are not so important yet, and my high IQ compensated for a lack of focus. Only in secondary school it became a problem, and my grades dropped.