Earlier quoted context omitted.
Orwell was a leftist, but also opposed totalitarian societies. "1984" was a dystopia to expose such totalitarian societies. Unfortunately, much of what he described as a horror scenario in "1984" is already reality today, without people being bothered by it anymore.
How do you define 'leftist'? Orwell also wrote Animal Farm, which is critical of communism.
As a younger man he was very much a Marxist revolutionary, but getting shot through the jaws in Spain and then subsequently witnessing the totalitarianism of Stalin quickly changed his mind. Animal Farm is a criticism of Stalinism in particular.