Websites like Kinguin, G2A, or Eneba list keys sold by individual merchants. If you choose this route, keep the following in mind:

Authorized retailers buy their stock directly from publishers. Buying from these sites guarantees a working key and directly supports the creators. Popular authorized storefronts include: Green Man Gaming Humble Store 3. Marketplace Aggregators

Since you can no longer buy the game directly through standard storefronts, you must look to authorized third-party retailers and reputable digital marketplaces. 1. Trusted Key Store Marketplaces