Employing Ghislaine Maxwell has to top the list. Changing their community rules definition of hate speech to only be against chosen groups has to count too. But there’s a lot of bad stuff that redditors quietly accepted, forgot, or newer members never heard of.
/u/maxwellhill on Reddit was suspected but never proven to be Ghislaine Maxwell, they went dark the same time as the arrests etc. they were a power mod across some huge subreddits like worldnews, travel, badcopnodonut, etc.
It’s a bit of a conspiracy theory in my opinion and fellow mods have dismissed it claiming they’ve seen/spoken to maxwellhill and but who knows, this type of thing takes off on Reddit, ala the Boston Bomber thing leading to that poor kids death. I take this stuff with a grain of salt.