They are feeling the pinch of going broke. That, or it's a flaw in some hate speech algorithm that mistakenly thinks that racism applies to White people too. One that's likely to be patched out, and result in all those channels that hate on the culturally acceptable targets being restored, apologized to, and compensated for their losses. After all, over 90 percent of all hate directed towards racial groups online is directed at White people, and the channels on a platform as large as Twitch are likely to be largely composed of people who hate Whites and aren't shy about expressing it in front of their audiences, often in very elaborated detail of just how intense their hate is for Whites, why this one race is inherently evil and responsible for every bad thing that ever occurred, not to mention how much they passionately desire for this one race to be entirely wiped out of existence, and will celebrate every day that time comes just a bit closer. Tldr I highly doubt twitch will start banning a huge population of their streamers from the platform, but if they truly want to crack down on racial hatred of White people, then that's exactly what they are going to have to do.