@[email protected] notified the community about a post on Reddit where a Redditor is seeing a message from Humble Bundle saying:
OOPS! THIS GAME KEY IS NO LONGER AVAILABLE.
IT HAS BEEN OVER 3 YEARS SINCE PURCHASE, EXCEEDING OUR TERMS OF SERVICE.
It appears to be sporadic and not for all purchases over 3 years old.
You may want to check your Humble account to see if you have been affected by this and reach out to customer support for whatever further assistance they may be able to provide.
I’ve seen claims that Humble may be hiding some valid, previously-revealed keys.
In other words, it’s probably a good idea to reveal all your keys and save them in a spreadsheet. You don’t have to claim them in steam so you can still trade/gift them, and I don’t think they typically expire.