Chrome: 80.0.3987.132
https://fomantic-ui.com/modules/calendar.html#24-hour-format
If you enter a time for this sample, the time selected in the popup is incorrect.
1 -> 0:00
1: -> 1:00
13 -> 13:00
Entering 2 digits works correctly.
This problem does not occur with FireFox.

This is reproducible.
0 .. 12 entered, 0:00 hour is chosen.13 .. 23 entered, the matching hour is chosen as same as in other browsers.: like 0: or 1:, the matching hour is chosen as same as in other browsers.
I will look into this issue and open a PR.
Fixed by #1569
Most helpful comment
I will look into this issue and open a PR.