No scientific studies yet unfortunately, as far as I know (though I have seen a study which found that non-native speakers are more likely to be falsely flagged as AI by detection software). But it is something that people are talking about, both automated detection and accusations from other people.
A quick Google search with the terms autism accused AI gives me:
Bloomberg article, talking about automated detection:
https://www.bloomberg.com/news/features/2024-10-18/do-ai-detectors-work-students-face-false-cheating-accusations?
https://archive.ph/kU77Q
Olmsted submitted a written assignment in a required class—one of three reading summaries she had to do each week. Soon after, she received her grade: zero. When she approached her professor, Olmsted said she was told that an AI detection tool had determined her work was likely generated by artificial intelligence. In fact, the teacher said, her writing had been flagged at least once before.
[…]
Olmsted disputed the accusation to her teacher and a student coordinator, stressing that she has autism spectrum disorder and writes in a formulaic manner that might be mistakenly seen as AI-generated, according to emails viewed by Bloomberg Businessweek.
[…]
The students most susceptible to inaccurate accusations are likely those who write in a more generic manner, either because they’re neurodivergent like Olmsted, speak English as a second language (ESL) or simply learned to use more straightforward vocabulary and a mechanical style, according to students, academics and AI developers.
Guardian article, also mostly about automated detection, briefly mentions the autism link:
https://www.theguardian.com/technology/2024/dec/15/i-received-a-first-but-it-felt-tainted-and-undeserved-inside-the-university-ai-cheating-crisis
Neurodivergent students, as well as those who write using simpler language and syntax, appear to be disproportionately affected by these systems.
Several articles about an autistic American university researcher who tweeted about being misidentified as AI from the tone of their emails; here's the NY Post one:
https://nypost.com/2023/07/21/autistic-purdue-professor-accused-of-being-ai-for-lacking-warmth-in-email/
Many blog posts, message board posts, social media posts etc. from people who've been falsely accused either by automated detection software or other people — just a random selection:
https://andrewggibson.com/2024/10/27/false-ai-detection-human-writing/
https://www.reddit.com/r/autism/comments/1eemf3e/accused_of_using_ai_but_im_just_autistic/
https://www.threads.net/@fork.ca/post/DF6dFLvsctR
https://writerethink.medium.com/please-stop-accusing-people-of-not-being-human-403f15476837
None of this is conclusive scientific evidence, but I think it's enough for initial suspicions that something may be going on there.
My own anecdotal experience is of having been accused several times (by other people, not automated detection), and while I don't think most people have that experience, I've come across several other autistic people who've also said it's happened to them.
There are also autistic people who say they haven't had it happen to them, and presumably it does also happen to non-autistic people, but it seems there are features that are more common in autistic people's writing that get picked up on.
It's also possible,I suppose, that autistic people are no more likely to be accused than anyone else, but because of historical preconceptions about autism, quite reasonably wonder whether the perceptions of their writing as computer-like are linked to those stereotypes. They also might be more likely to find the accusations hurtful and to remember them.
Apologies if any of those links don't work — can't remember if archive links are allowed.