I have no idea, since I'm an iOS dev, not a web dev. We've seen a lot of these coding exercises btw, but the ones I've done have been onsite, so there is no way someone could of spent more than 2 hours on something. Usually the standard is if your able to complete the exercise, that's pretty good! I've only seen tests written once or twice, mostly because there was no time. You also see a lot of shortcuts due to the time constraints. You go through and explain your code, so you can point out 'this is a shortcut, normally I would do XYZ".
Usually when someone makes something 'too good', it usually means they've leveraged libraries that they already know. If they make a lot of code, I know they probably spent more than 2 hours. By making it a weekend project, maybe they are subtly hinting that better candidates will spend more time on it, which I think is shitty and one of the reasons why I don't like homework questions.
I'm assuming for all of the things you've just said, it means you are using libraries that make a lot of those things one liners. Like read/write local storage, search a data struct, reactive UX changes, etc.