you only encounter it by interacting with the browser in an atypical way
Leaving my pointer on a random place that happens to be a link is atypical? I don't think it is. I had this pop up to me a couple of days ago and I didn't even understand what could've triggered it, I was wondering if I clicked something or pressed a key unconsciously.
and the thing it does is a thing that AI is actually pretty decent at (summarizing text)
Pretty decent? Just passable, if the text is about some run-of-the-mill topic.