Yep, this is a subscription-only offer for those with a future renewal date. Just like how the previous ones have worked so far.
Edit: You’ll need to maintain the renewal (which you didn’t) or start a new 6/12 months subscription to receive the rewards.
If you’re currently on a 6-month or 12-month recurring subscription with a future renewal date, you’ll receive the mount and pet as a gift in your Battle.net desktop app at no additional charge no later than July 23, 2024 (must be redeemed by January 31, 2025).
Also, if you’ll be eligible it will be in your launcher app, under gifts. After relogging it will be in your collection to unwrap.