Steps to reproduce the issue

ADMIN - USER - Profile - Date of Birth
LANGAGE = FRENCH (User and Admin)

Expected result

Help message mislead User as they ask to enter date in the US way YYYY-MM-DD
But if Langage(date) is set to FR : date must be enter in DD-MM-YYYY
Translation help (translation) tell user to enter WRONG format which cause Users to fail to enter their date of Birth...

Solution - FIX - Workaround

Modify translation file : administrator\language\fr-FR\plg_user_profile.ini

Change lines 15-16-17 to reflect correct French langage:

PLG_USER_PROFILE_FIELD_DOB_DESCRIPTION="Jour-Mois-Année, par exemple 27-01-2019." ; Adapt to the format you entered in the 'DATE_FORMAT_CALENDAR_DATE'
PLG_USER_PROFILE_FIELD_DOB_HINT="JJ-MM-AAAA" ; Adapt to the format you entered in the 'DATE_FORMAT_CALENDAR_DATE'
PLG_USER_PROFILE_FIELD_DOB_LABEL="Date de naissance"

System information (as much as possible)

Tested under Joomla 5.22

Additional comments

Update to pass to Translation fr-FR Team (Mihaly)

BR, Gilles