If you are referring to the thickness, the cursor thing isn’t a bug, and if you’ve never seen it before, you perhaps only use a few programs that use native Mac text editing interfaces.
Otherwise though, it should be shorter than that, and the other thing would also be a good clue to make sure you’re up to date with Scrivener (for one thing it applies fixes to cursor height, as Apple seems to want it to be as tall as the whole line rather than just the visible text, kind of like this).