What does updating / jailbreaking have to do with Discover Cashback?
Devices using lower versions of iOS should be able to get the 10% (or 20% for some), as well as if the devices aren't jailbroken. Last I checked, the bonus was for using Apple Pay in-stores.
Don't get me wrong, I've been jailbreaking for years. Just not sure where you're going with this thread.
Or did I miss something?