The Date Picker control needs a "HintText" property.
I have created a customized SharePoint form in PowerApps, and I have two fields on the SharePoint list: "Commencement Date" and "End Date". The fields are not mandatory, and have been configured with a default of "(None)".
When you go to create a new list item, the customized PowerApps form appears, and for each date field it shows a hint text of "31/12/2001" (The date format for the date pickers was set to "dd/mm/yyyy"). This is confusing users, as they are trying to specify "No Date" somehow.
It's also confusing them even more when they view an existing list item, because even though no date was set, it's still showing as "31/12/2001". Even though the date appears greyed out, it's not obvious to the user that "no date" was set.
Form in Edit ModeForm in Display Mode
'By adding a "HintText" property, instructions could be placed in the picker, such as "select a commencement date". Then in display mode, if nothing is selected, the HintText is not shown so that the viewing user is not confused.