Thanks Emanuel,
Behavior: User Local + Format : Date Only actually means that the date is displayed as date field, but it still contains a hidden time part in the user time zone, set to 00:00:00.
So if I set today's date in that field, I will see 2020-11-20. But it will in fact as store it as 00:00:00 my time zone (say CET).
In the system DB, it will be stored in UTC, so 2020-11-19 23:00:00 hence potentially displayed as the day before for some users in earlier Time Zone.
I suspect calculated fields take the UTC value, so potentially with day difference in some situations (user setting the date from a different Time Zone, daylight savings...)
This article covers the various Date/Time behavior: Working with Time Zones in the Common Data Service | Microsoft Power Apps
One way to mitigate this, would be to change the behavior to Date Only (if that's indeed what you're trying to capture) - that's not reversible though.
Henry
