Redeem Steam key to account with Steam OpenID like Humble Bundle

Humble Bundle has started requiring the user to sign in through Steam's OpenID authentication where it then redeems the Steam key on the user's account. I was unable to find any documentation on this

Does Humble Bundle give Steam keys & how to redeem them

How to Redeem a Gifted Bundle or Game – Humble Bundle

Steam (service) - Wikipedia

Does Humble Bundle give Steam keys & how to redeem them

PSA] Humble Bundle ran out of Steam keys for Back 4 Blood : r

How to Buy a Humble Bundle and Redeem It on Steam

Popular Brand Icons – Simple Icons – WordPress plugin

I was previously trade banned on Steam. I made another account

Steam] (game) Dungeon of the Endless + DLC : r/FreeGameFindings

I made a tool that automates extracting and redeeming ALL Steam

Does Humble Bundle give Steam keys & how to redeem them

Steam Key Redemption – Humble Bundle

How to Link Your Steam Account – Humble Bundle

Free Game Redemption Instructions – Humble Bundle

I randomly got this message today for a game I got in a Humble