Providing the service is selling groceries, that doesn't require a birth date.
So it's not possible to sneak it under performance of contract. Only Legitimate Interest or Consent could be valid, and you can oppose/retract.
But good readng, please provide our findings, that will save me a reading 😅
It's rather the other way around, Word is not 1 to 1 compatible with LibreOffice Writer when it comes to document editing. Writer is far better on that aspect.