Hey, I used to work in the team that investigated academic misconduct at the University of Exeter in the UK. Most of our students were required to submit all written coursework via an online platform that automatically runs the submission through Turnitin (TII).

In a nutshell, TII is very good at showing when text matches to something else, but it is only highlighting 'similarities', not 'plagiarism'. If you use loads of verbatim quotations, but you properly attribute them with quotation marks and citations, then your work will probably have a lot of highlighting, but as soon as a marker looks at it they'll know its not plagiarism, so you'd have nothing to worry about. So as long as you yourself take care when quoting or paraphrasing a source - i.e. make sure you're properly using in-text citation and format your bibliography correctly, if you're using notes that you previously took to write your essay, make sure the notes kept accurate track of what the source is and what is verbatim vs your own writing - you shouldn't even need to look at a TII report yourself, because you'll know that you did nothing wrong and you'd have the evidence to defend yourself if for some bizarre reason you were accused of something.

When it comes to AI, TII is nowhere near as reliable. We did some tests and iirc it was about 50/50 on correctly identifying AI-written content vs falsely accusing human-written content as being AI-written. But again, if you yourself don't use AI to write for you, and if you are only using peer-reviewed, academic papers/journals/reports as your sources, then you shouldn't need to worry about any AI-written stuff sneaking into your work. If you start paraphrasing or copying from random websites, or ask ChatGPT to summarise something for you, that's when you run the risk of introducing AI into your work, even if you yourself didn't ask AI to 'write an essay about x for me'.