The specific practical matter is that the last actual official Mississippi Flag contains, in one corner, the flag which people think of when you say "Confederate flag" which has specifically been called by Twitch for its association with slavery in America. While the Mississippi flag might in select contexts be used to mean "white supremacy," it also means things that are not identical to the concept of white supremacy: for instance, it means "Mississippi". Is this enough of a difference to allow the Mississippi flag, or is it still associated with slavery in a strong enough matter that it should be banned?

One recurring problem with speech codes is ambiguity of this sort. Even though the guidelines Twitch has provided are much more detailed than most online chat platforms have deigned to make available (cough Discord cough) there is still nontrivial ambiguity over these matters — ambiguity which can only really be resolved by authorized representatives of Twitch itself. In the broader world, when such ambiguity exists in the law, we have things like a court system with evidentiary standards and a presumption of innocence; these are things we lack on Twitch.

Why would you think that? Where do you come from?

USSR insurrection were from their southern borders. If i remember something from highschool, those are not white europeans, but mostly Turkomongols and Tatars. The USSR integrated most of Transoxiana, and and financed conversion to atheism, how could this possibly end well?