Recover proxy bypass list from System Preferences
This information is stored in

/Library/Preferences/SystemConfiguration/preferences.plist


Under the NetworkServices dictionary are each service in the Network preference pane. Look through the list until you find the service with the matching UserDefinedName such as Wi-Fi, then open Proxies and see the ExceptionsList array.



You can recover an older version of this file from your backups such as Time Machine, or from an APFS snapshot.