In short, yes!
Adding a customer's date of birth from the Happy Birthday app to their Shopify Customer Profile has always been possible via customer notes or tags, however, you can also choose to add their birth date to a Shopify customer metafield.
We have an article that covers how to set up storing birthdays in Shopify Customer Metafields
Need any help?
If you would like any advice or support related to storing birth dates in customer metafields, then please don't hesitate to get in touch.