[itsme]

I still vote for a unique prefix and prefer MobileSheetsPro_ over MobileSheetsProBackup_

Using the Windows date&time settings here is not my favorite (but I can live with it if I have to).
Changing the Windows date & time settings would mean that everywhere in Explorer and so on the date is shown as yyyy-mm-dd.

Using a date as part of  a filename is not the same as setting a date format to display dates. It's about sorting.
In Explorer and so on it is known that it's a date and it is sorted as expected, no matter what date format is used. yyyy-mm-dd in a file name takes care that sorting alfabetically shows the same result as chronological sorting.