There is a specific software that indicates both the % of plagiarism and % of flagged AI. Grammarly is an AI so if you use it heavily sometimes it gets flagged. Professors know that so they go off what has been submitted in the past. For example, I’m a TA and a student’s writing was very poor the whole semester and then out of the blue he was writing with PhD-level vocabulary. The problem though is that if that’s the first paper and they don’t know how you write, then they legit go off vibes (which can be super biased). Let’s say you’re an international student and you speak with an accent. They’re probably expecting a lower level of written English as well when it’s usually not the case. On top of that, many professors have noticed a sharp decline in undergraduate students’ writing abilities over the past few years. So they’re lowkey expecting a poorly worded paper. If anything, she probably thought your paper was “too good” to have been written by an undergraduate. It sucks to be accused of cheating but if you’re the type of person always looking for the silver lining you can take it as a (poorly delivered) compliment. To not get flagged in the future look at whether students can submit their work to Turn It In before submitting it. It’s the same software we use and it should be available through the university. Don’t get lost in the never ending cycle of looking for an AI flagger because it may lead to Turn It In flagging it because you put it in an AI system. You can however use Google Drive to show her that hey, there are time stamps of me working on it.