But that is exactly what is happening if you press Ctrl+F in a topic with lots of posts. Try it out yourself by pressing it inside a topic with more than 20 posts.
And it is good that this is happening since I want to be able to search using my browser. It has a better search experience. My problem right now is that the Discourse search window stays visible and I get lots of search results from the browser that are within Discourse’s search results. See my screenshot in the first post.