There is a more compact, less ambiguous, more universal format in my opinion: ddMMMyyyy, e.g. 28feb2021.

Yes, it's English month abbreviations but few people worldwide would not be able to take the obvious meaning.

(it's a MIL/NATO standard afaik, and has been in use for 50+ years)

(edit, timezones are single letter, e.g. Z for Zulu aka UTC)