System time format is not honored

In the GitLab preferences, the time format is set to “System”. As my system uses the 24-hour time format (see below), I would expect to get that on GitLab. But I get the 12-hour time format (with AM/PM) instead.

I’m using Firefox, and in its settings: “Use your operating system settings for “English (Denmark)” to format dates, times, numbers, and measurements.” is ticked, so that this really corresponds to the 24-hour format. A test in a shell:

$ LC_TIME=en_DK.utf8 date -d @1708900000
2024-02-25T23:26:40 CET
$ LC_TIME=en_US.utf8 date -d @1708900000
Sun Feb 25 11:26:40 PM CET 2024

Is there any reason why the system time format is not honored?

Note: I could change the settings to the 24-hour format explicitly, but

  • this does not work as documented, so there is an issue that needs to be solved;
  • it would be a bit annoying to have to change the setting on every GitLab instances;
  • it is generally better to have the configuration at one place.

EDIT: note that I get this issue all the instances I tested: