Real typing is messy. You think a few sentences, you type them, you pause, you fix a typo, you keep going. Google Docs does not record every keystroke — it batches your edits into short intervals and saves each batch to version history with its own timestamp.
Paste a finished draft and version history shows one giant insertion at a single timestamp. That is the tell. Anyone reviewing the doc opens File → Version history and sees a wall of text appear instantly with zero activity between sentences.
AutoTyper writes the same draft the way version history expects to see it: as a sequence of small chunks paced across the window you picked. Pro adds two extra layers — occasional typos that get corrected later in the same draft, and a small revision pass after the main typing finishes. The result on disk is a timeline that looks unmistakably hand-typed, even though you wrote the draft elsewhere.
This is also why we never let the run finish too fast. A 1,500-word draft typed in three minutes still looks suspicious. The same draft drip-written across an hour or two reads like someone working through a paper.