After some posts about HumbleBundle adding expiry dates to keys after the fact it looks like it's not just restricted to Humble. Fanatical made a timely update to their help page a few days ago:
The game keys you purchase from fanatical.com should be redeemed within 12 months but the warranty for the keys is 30 days. Technically speaking as long as the publisher doesn't remove the game from the platform through which they are redeemed they should be redeemable for longer but publishers have been know to removed unused keys from Steam after 12 months.
Edit: Humble have sent out their first announcement/warning this morning:
A friendly heads-up that game keys for DEATHLOOP, which was part of your October 2022 Humble Choice monthly mix of games, are expiring January 2, 2024.
If you haven’t already done so, reveal your key today so you don’t miss out on your game. If you already revealed your key, you can disregard this notification.