My wife works at a European engineering university with students from all over the world and is often a thesis advisor for Masters students. She says that up until 2 years ago a lot of her time was spent on just proofreading and correcting the student's English. Now everybody writes 'perfect' English and all sound exactly the same in an obvious ChatGPT sort way. It is also obvious that they use AI when she asks them why they used a certain 'big' word or complicated sentence structure, and they just stare blankly and cannot answer.
To be clear the students almost certainly aren't using ChatGPT to write their thesis for them from scratch, but rather to edit and improve their bad first drafts.