I purposefully kept the comment vague to avoid a dumpster fire. Basically, there are certain mental health conditions whose classification/categorization/etc. seem especially vulnerable to politicking, and if you take a dissenting stance on those particular conditions, you'll be attacked by opponents who believe the DSM grants them scientific high ground.

You would know if it's happened to you.

Try mentioning any of that and you summon a lynch mob. That area of science makes cargo culting in software development seem like math. Utter joke. That anyone takes it seriously or actually does anything based on it.. surgeons during Napoleonic wars had more clue as to what they were doing.

I suspect he's referring to Gender Dysphoria, which was previously known as Gender Identity Disorder. This, if I recall correctly, happened in the transition to DSM 5.0.