alt Hacker NewsNote that she was following her lawyers advice. Not a gag order from Meta. This advice l is standard practice when you have an active litigation against you (everything you say can and will be used against you).
Edit: I stand corrected. See comment below.
There is apparently a court order involved:
"Meta, which owns Facebook and Instagram, secured an emergency legal order on the eve of publication preventing her from publicly discussing aspects of the book, and she faces fines of $50,000 (£37,000) each time she breaches the order."