Login items comes immediately to mind.
For my laptop I had to change the priority of networks. This is logically under “Network”, but not at the top level and there’s no hint where it could be. I see now that it’s buried under the “…∨” button.
Side note: That button is an abomination. I get that the “three dots” has become a button that means “more stuff buried here” on iOS, but on Macs it has — since the very beginning! — always been paired with a menu command to indicate that selecting the menu option won’t actually do anything and that you will be presented with some sort of dialog box to make further decisions before executing the command. Now it has a totally different meaning. And an ugly downward-pointing arrow next to it, as well.
If the items hidden under this mysterious button are advanced settings, why not use the familiar “Advanced”?
In fact, why not just list them on the main Network page under an Advanced heading? Privacy & Security is a huge scrolling list already (with an "Advanced… " button, I note) so why not use the blank space?
A final example: why are Extensions under Privacy & Security? I mean, from a computing point of view, it sorta makes sense. Here is where you can turn additional, and possibly insecure, things on and off.
But if you think about it logically, when I have to, for example, set up Photos so it can send one of its images to be edited inAffinity Photo, my intuition does not suggest that this is a privacy issue, or a security one. Apple had a chance to fix this kind of bad design, and they chose not to.