All media is not propoganda.
All media suffers from bias. Though some places that's a deliberate editorial line - while other try to avoid that and will be more affected by the individual bias of their journalists. Because you can try to be un-biased, but the questions you ask are coloured by your experience, beliefs and expectations.
There's also groupthink, particularly a problem if you're recruiting from a limited pool of people with similar experiences.
But propoganda is a deliberate choice. It's different from bias, because it's an attempt to skew the facts to give the editorial line you want - and not report facts that don't meet that line. Whereas a bias can be unconscious - and good media organisations that have an editorial line will try to separate their news and comment.
RT is propoganda. It's about trying to de-legitimise democratic systems in a sort of nihilistic attempt to claim that although the Russian sytem is awful, the democracies are no better. An argument that's clearly bollocks. Although obviously our systems are far from perfect - which is the whole point.
At least in the early Soviet days there were people who genuinely believed in Communism. But the current Russian leadership will have mostly joined the KGB in the 70s and 80s - when it was clear their system was both evil and rubbish. So they'll have been a generation that joined the party, cynically, to get ahead. And then the KGB, where a lot of them got involved in corruption. And they've nothing positive to say about their system - hence the campaign to attack ours.