Any iPhone app crashes whenever time radio dial is pressed Problem
A few weeks ago, I noticed that I could not add any new alarms on my iPhone.  Eventually, I figured out what was going on:

Whenever I press any button that launches a time-based radio dial (one of the pop-up context menus that has you choose a time or date), the app crashes.

Attempts to Fix It

I thought this was just a problem with the Clock app (I just use the standard iPhone clock), but when I tested other apps that have the datetime radio button, like the transit app I use, the same problem occurred.
I don't seem to have any other problems, other than this time-radio-button.  No other problems on other apps, and the phone otherwise is working fine.
I have tried all of the standard means of trying to fix something while in ignorance:

reboot the phone
reset all of the settings (that was a pain, but I did it)
uninstall and reinstall the offending apps


None of those efforts worked, and Google searching, I couldn't even find anyone who had a similar problem.
There was even an iOS update recently, and after the update, the problem was still there.

Any ideas on what could be causing the problem and what I might be able to do to fix it?
My iPhone details:

iOS version 14.2
iPhone Xs (model #: MT9J2QN/A)
256 GB, with 214 GB free
Wow, after struggling for a while, I finally tried something that should have been obvious, and it worked:

I changed the time format from 24-hr to 12-hr, and now it is working OK.
To be clear, in case anyone else has this problem:

Settings ==&gt; General ==&gt; Date &amp; Time ==&gt; Toggle 24-Hour Time off



I do not understand why that worked; I have been using the 24-hr clock since I owned the phone a little over a year ago, and this just started happening a few weeks ago.

Does anyone know where I can report this to Apple?  I suspect some auto-update introduced this bug, but I have no idea how to tell this to people who can actually track it.
(Too bad Apple does not use GitHub for anything...)