The offer appears in the "Account → Offers & Rewards" section of the Xbox menu, where the card is accompanied by a thank you message. The gift can be used immediately or later.
The promotion is valid until December 31, 2025. The received $10 can be spent on games, DLC, in-game currency, apps, and subscriptions in the Microsoft Store and Xbox Store.
Microsoft has made similar surprises before, but they are never announced and are selected based on region, activity, or purchase history. Not everyone will get a card. The received bonus can be used during holiday sales in the Microsoft and Xbox stores.