As of late June 2023, ETS has published 23 Academic Discussion tasks for TOEFL Writing. They are in the subjects of:
business
education
ecology
economics
political science
psychology
public policy
sociology
In other words, social sciences. It makes sense for ETS to use social science topics because they are topics that people disagree about. I will not be surprised to see tasks from other social sciences, such as anthropology, geography, law, and linguistics.
It seems to me that the hard sciences and literature/history are too difficult for this task. Also, there are already plenty of biology and paleontology tasks on the integrated writing task.
The questions are similar to the independent writing questions in the Official Guide to TOEFL iBT. Some of them are open-ended (you can write about anything you like), and some of them are forced choices (choose one of two choices).
With this logic in mind, I’ve written 32 academic discussions (and am continuing to write more). E4TG will begin offering an online (by email) Academic Discussion scoring service in late July, 2023.
For more information, contact Donald at toeflcoach@gmail.com.