A prod.keys file from 2021 will work for games released up to that specific firmware version (roughly version 12.x or 13.x).
Essentially a copy of your prod.keys file but renamed with a different extension. SAK often requires this specific filename in its bin folder to function correctly. How to Resolve "Missing Keys" Errors in SAK sak are the keysdat prodkeys correct 2021
Whether keys from 2021 are "correct" depends entirely on the game you are trying to process: A prod
While users often search for them interchangeably, there is a slight technical distinction in how SAK uses them: sak are the keysdat prodkeys correct 2021
The standard decryption file derived from the console.