Apple’s iOS is definitely a user-centric mobile operation system (for regular users, not so much for geeks and hackers). Its thoughtfulness also goes beyond the UI as I’ve discovered an interesting feature about the keyboards on the lock screen.
I typically use one keyboard in the system, say English; I can add more keyboards, e.g. German. If I set a new lock screen password (in “Settings > Touch ID & Passcode > Change passcode”, click the “Passcode Options” and select “Custom Alphanumeric Code”) while I have those two keyboards and then remove the second keyboard (German), iOS will still remember the keyboards set and will allow you to pick either on the lock screen even though you now only have English in the system.
This behavior is both confusing (why do I see two keyboards if there is only one currently added in the Settings?) and logical (iOS apparently doesn’t track which keyboard(s) you actually use while typing the password, so it has to give you the same set of keyboards so that you’re able to type the same characters from different ones). It’s also a small information leak from your device indicating which keyboards you had at a point in time.
The “fix” for this confusion is to set the same (or new) password again with the current set of keyboards you have.
ps. Note that iOS is not only user-friendly, but at times becomes very frustrating to work with. One of the worst things of the locked system is that there is no solution for backing up the device completely; iTunes/Finder backup the app data (but not caches), but not the system version or applications themselves, so restoring the system fully is not fast, nor painless.
I updated an old iPhone to iOS 12.5.1 recently and that has been an epic fail; a bunch of applications were downloaded from the store on their own and some were crashing or had missing data after that; I was utterly surprised to find 35 waiting updates in the store even though the OS had just had to download those applications. After updating, a few applications continued behaving in the same bad way. I wasted an unreasonable amount of time trying to make it work, but in the end I had to reset the device and restore from iTunes backup. Those applications worked well after the restore. It was a disaster, I’ve never had such a bad iOS upgrade before.