That's unfortunate... you need the seed/private key that matches that xpub... without it, you will not be able to co-sign any transactions from your Linux wallet...

Have you tried restoring your 2FA wallet with the 2FA seed and "Keep"ing the 2FA functionality... rather than "Disable"? After it is restored, checking what xpubs it has... see if any of the three xpubs in the 2FA wallet are "xpub67z"