Changing date/time format for entire nextcloud to international standard

I noticed when using the “Tasks” add-on that the date/time format when choosing a “start” or “due” date is a bit weird.

It looks like it follows the setting in “Locale” under personal info. Is there a way to set this to show dates using the international standard (as defined from 1988 and onward in ISO 8601) instead of the weird formats used by any country on the drop-down list?