Even my "ancient" iPhone X does it so rarely, I don't lose any context. Even if it's happening more frequently than I notice, the apps also restore their contents.
macOS supports context restoration for 7-8 years now at least. iOS has inherited that soon after, so any application "killed", they SHOULD return to the state they exited, given they are implemented correctly.
macOS supports context restoration for 7-8 years now at least. iOS has inherited that soon after, so any application "killed", they SHOULD return to the state they exited, given they are implemented correctly.