Perhaps via youtube's search and recommendation algorithms optimising for misinformation as an engagement strategy?
Is there proof that they are?
I encourage you to have a look at Guillaume Chaslot's https://algotransparency.org - it identifies what videos YouTube's algorithm most often recommends, based on a given search. Serious question (I'm not trying to be facetious): looking at those recommendations, what do you think?
That is not proof. It's cherry picked topics for uncontrolled Youtube recommendations to a bot account they created. I think nothing about that is scientific and it screams tech illiteracy.
Google ads were also used substantially during 2016 [0]. Google’s ability to target messages to demographics that they only know because of their data trawling is effective for selling garage door repair and election influencing.