Check Your Xbox Console or Xbox Mobile App for the Message:
Spring Sale starts today! Here is a special gift to help you make your first game purchase. Enjoy this $10 USD Gift Card you can use to buy Games Add-ons and Movies on your Microsoft Store online.
Redeem your gift card on console or Xbox.com/RedeemCode by 4/30/2021 and spend within 90 days of redemption. See full terms at Microsoft.com/CardTerms
As usual in the past this is YMMV and can vary in amount.
Redeem codes here Microsoft/ Xbox Code Redemption [microsoft.com]
FYI. You can redeem now if you need it otherwise you may want to wait until 4/29/2021 to give yourself an extra month total 4 months before the balance expires.