It appears Google's AI overview is really just RAG over the top search results (= search stuff on the web given the user query, let LLM answer query given the contents of search result)
Naturally, redditors have started poisoning search results. Google ranks Reddit very highly. This issue is basically not fixable unless Google largely ignores Reddit content except for known good content, or develops a model they can use to filter adversial content (which is basically impossible)
Glorius.