I can't read the OP, but, it seems quite impressive if the matriculation rules already have "must not use AI assistance" in them. Would be interested in the particular wording too - if you used ChatGPT search tool does that disqualify you? What about if your spreadsheet app used AI to choose the best graph type? You used ChatPDF?

Are they saying it is plagiarism, would students know that it was considered that way (you've not copied, and ChatGPT isn't a source as such).