I would say that disinformation can come from both.
Right now, I'm quite struck by what's happening within Canada and how people are able to spread false information. As your colleague was saying, it seems that responsibility, accountability and truth are no longer important.
Perhaps it would be a good idea to come up with a set of rules, so that people can't change the names of the parties or associate them with false information in the House, for example. People must be able to discuss the real issues, rather than having debates where everything comes down to personality or turns to personal matters, because that's where things start to go sideways.
Certainly, everything related to truth, fake news and disinformation is currently becoming more central to the ethics that political actors will have. This plays a role in the way people will want to communicate with each other, as well as with voters, of course.