When searching a specific topic alone - somebody said “As Chris said” in the topic and I didn’t recall their being a Chris in there so I wanted to search on it. Understand requiring a longer search when searching the entire forum.
No, on long posts, Discourse will use its in-topic search when you press CTRL+F, you can press it again to get the browser one, which would be limited to what is loaded in the dom. The Discoruse in-topic search is not limited to what is in the DOM.