WHO section IDC-10 still considers it as such. The american DSM still does as well, just in much more politically correct terms.
Of course, once again, a favourite of leftists is to obfuscate and degrade language until it is meaningless.
Mayo clinic describes mental illness as the following:
Mental illness refers to a wide range of mental health conditions — disorders that affect your mood, thinking and behavior. Examples of mental illness include depression, anxiety disorders, schizophrenia, eating disorders and addictive behaviors.
Many people have mental health concerns from time to time. But a mental health concern becomes a mental illness when ongoing signs and symptoms cause frequent stress and affect your ability to function.
So it certainly fits. It just isn't acceptable to left wing identity politics to say so. Again, is being gay a choice? That was the question pushed for years, with the left screaming it wasn't.
So by any possible logical conclusion, it certainly is (edit- a mental illness). Can't have your cake and eat it too, I'm just going by the lefts definitons