In the ACF documentation, it is said that the field type date_picker can customize
Save Format
and
Display Format
However, when I look at a date picker type field on ACF, I see options for
Display format
The format displayed when editing a post
and
Return format
The format returned via template functions
Do I understand correctly that I can’t or don’t have to change the Save Format anymore, and that documentation has simply not been updated to reflect that?
I think that you are right and it’s just that the documentation has not been updated. As far as I know ACF saves all dates in the format YYYYMMDD.