Airtable has its own settings for dates that do not always match the computer settings.
By default, Airtable dates are MM/DD/YYYY.
Airtable thinks that 03/08/2021 is March 8, 2021.
If you want that 03/08/2021 to be 3 August 2021, I recommend changing the format of your date field to be “European”. You may find that you need to redo your data entry.
When you format your date using DATETIME_FORMAT you have the option of setting both the locale and the order of the elements in the date. Setting the locale in the DATETIME_FORMAT only changes the words used, not the order of the words.