Just did my own bit of googling and came up with a number of stories like the Guardian piece about journalists etc infiltrating far right groups, because the bleating of "fake newsflash doing my head in.
As an aside, propaganda was the biggest Nazi tactic used to focus hatred, and widespread use of relatively new at the time, but becoming more mainstream, technology, ie radio and film was a fertile breeding ground.
Of course back then it was carefully curated by a political party openly seeking power, however today things are so much more complex when virtually anyone with a smartphone and a few apps can throw out any bilge they choose potentially to an audience of millions, and with the advent of ever improving AI it's very difficult to know what's real and what's not.
Any platform can be infiltrated, and of course on anonymous forums it's not always easy to sort the wheat from the chaff so to speak. Cambridge Analytica proved the power of the Internet in terms of deliberate skewing of political outcomes, but unfortunately because money is more important than anything else, and the amount of instability in the world, turning the tide is extremely difficult.
That Guardian article was chilling.
Also, we have the 77th Brigade pushing our governments agendas online too, which is supposed to be our cyber defence in combating online radicalisation, but given the lack of trust in the last two governments I'm not sure how effective they are.
Anyway, apologies for the slight tangent, it's just a whole area I'm particularly interested in.