The radical Bolsonaro whatsapp groups are a mix of top down and grass roots content. On one end there is the central "propaganda office", or other top political articulators. On the bottom are the grassroots group chats: neightborhoods, churches, biker communities, office mates, etc. Memes and viral content flow in both directions. The contents and messages that ressonate in the lower levels are actively distributed by the central articulators, which have a hierarchy of group chats to circulate new propaganda as widely as possible. You can see this happen in real time when a political conundrum happens,e.g a corruption scandal. The central office will A-B test various messages in their group chats and then the one that resonates better with their base gets amplified and suddenly they manage to "change the topic" on the news. The end result is that we just had 4 years of political chaos, where the modus operandi of the goverment was to put out fires by deflecting the public discourse whenever a new crisis emerged. It's not merely a content problem that could be solved by a better filtration algorithm. It's a deeper issue of how social media can affect human behavior. How quickly ideas can spread, how easy it became for people to self-organize into "bubbles", and so on.