I just noticed this issue and began writing a bug report. Here's how I described it:

---

Superset should respect the system time format setting.

In iOS Settings → General → Date & Time, I have the option “24-Hour Time” enabled. However, Superset still displays times using AM/PM. It would be nice if times are displayed consistently with the system setting.

Someone already submitted this feature request and it is already tagged as Planned. You can check it here

Hey, thanks for the feedback! I'll add this to the roadmap to allow get Superset to follow the system time setting