I'm not surprised it's Terry at all. I heard about this from another post on The Shortform recently, and guessed it was Terry L Cooper. If it's any comfort, I've seen other posts from her, criticising all sorts of publications for alleged 'errors'.

What she says is bullshit frankly, because the post in question (her post) was full of errors. I don't believe she's a pro writer. She's totally dependent on software to tell her how to write English. And it often fails to do that well.

My first experience with her was just after I joined Medium, and it was horrible. I wrote about it, but didn't have the nerve to publish for three months! She told me my work had 83 errors. It didn't have any errors and she was talking shit, because she relies on fallible software.

She's since been fired from Illumination for this reason. My post may interest you if you haven't already seen it... https://medium.com/writers-blokke/when-illumination-said-my-work-had-83-errors-e5e2d152d305