From: https://world.mendix.com/display/NRG/Attributes
Localize (only attributes of type 'Date and time')
This property indicates whether the date and time should be localized. By default localization is enabled. If you are not interested in the time component of a date (e.g. a birthday), you should set this property to 'No'. Otherwise, the date can change because of time zone differences: a date and time early in the morning on April 2nd in Europe will be on April 1st in the U.S.A.
Default value: Yes
Maybe it answers your question, i guess not. (It did not answer mine related to this question)
Dates are related to a given ('local') timezone. If you turn localize off for the date attribute, it means that the date is stored as if in UTC timezone. This is independent of the server or workstation timezones, when displayed or entered on the screen. So any person in any part of the world will be presented the same date, as it should be with birthdays for instance.
Probably displaying the DateTime in the country specific way.
For me the question still is database datetime or workstation datetime ?