The problem wasn’t that the line I wanted wasn’t on the page—it’s that the whole document wasn’t being rendered at once, so my browser’s builtin search bar just couldn’t find it.
I feel like this has been the case for a while now. Luckily they offer other search tools so its a gotcha that you only have to hit once.
In edit mode they capture the crtl-f keystrokes and offer their own search and replace tool. An argument could be made that they should offer a custom search tool for read mode if they are going to break the browsers built in tooling.