Looks like an overzealous "type-ahead" matching. I can automatically get values that I've pre-selected by typing the first digit(s).
I'd say also broken. Please report in the new Tracker system: https://tracker.adobe.com/#/home
Nice catch, I'll mention the behavior in my book and courses!
You cannot type directly into the box but can set your preferred zoom percentage.
Once set you can select it from the list.
It is as designed in this version but nevertheless you can log a bug in the tracker as Arnis mentioned above and we will take a look.