Your writing was flagged, and you want to know why

What goes wrong

An AI detector returned a number you did not expect on something you wrote. The frustrating part is that it will not tell you what it weighed, and some of what it weighed is genuinely in your file while some of it is a guess about your style.

Two different things get counted. Invisible characters are objective: if a zero-width space or a narrow no-break space is in your document, it is there whether or not you put it there, and it usually arrived by pasting a quotation, a research note, or a paragraph you asked an assistant to rephrase. Typographic habits are the other half, and em dash frequency is the single most cited one, because models produce them far more often than people type them. That half is about how you write, and a detector treating it as proof is overreaching.

What to do about it

Separate the two. Run your draft through the cleaner on this site and see the census: that is the part you never chose and can remove without changing a word of your prose. What remains is your writing, and if a detector still objects to it, you are arguing about style rather than evidence, which is a much better argument to be having.