I spotted this article in the Guardian.
The anger focuses on the character of Mindy Park, who is described as Korean-American in the book and played by white actor Mackenzie Davis
Ridley Scott accused of 'whitewashing' Asian roles in The Martian
But I don't recall and any specific references in the book to Mindy Park's ethnicity and while it's true that Park is a somewhat common Korean family name, it's also a somewhat common Anglo-Saxon family name.
Were there references to her ethnicity that I missed?