This article (in Spanish) considers how the word “functioning” anticipates the capacity of development in people with autism, giving either high or low (never medium!) hope . The author suggests that this is reductive and does not take into account the diversity of people on the spectrum or even outside the spectrum. People without autism do not always “function well” nor do they represent necessarily an ideal to be measured against.

How we function depends a lot on our environment. Before deciding whether a person is high or low functioning, shouldn’t we look first into adapting the environment? Or try to create an environment more accepting of others’ differences?..

https://autismodiario.org/2017/06/12/la-funcionalidad-no-funciona-autismo/