The tells are in the cadence. And the not x but y. And the last line that basically says nothing, while using big words. It's like "In conclusion", but worded differently. Enough tells for me to click on their history. They have the exact same cadence on every comment. It's a bit more sophisticated than "chatgpt write a reply", but it's still 100% aigen. Check it out, you'll see it after a few messages in their history.