Clearly this is a bug on (Xojo?) MacOS side:
Note i use DateTime instead of Date since “Date” is deprecated.
Windows DateTime instance (works correctly):
Note: Windows has one bug an that is DateTime.DayOfWeek shows 2 while it should be 1 since the day starts @ monday and the day on the image below is monday:
Windows FolderItem.ModificationDateTime:
Both Date and Time seem to be correct in “Europe/Amsterdam” or GMTOffset 3600