Board Thread:Episode Discussions/@comment-1181222-20170802095306/@comment-25122992-20170802145526

It doesn't indicate anything at all, just the different colouring. It's kinda not the first time of anime changing colours of something. Plus, we don't even know the exact definition of "pure" Byakugan, it was just mentioned by Toneri as a reference to Hanabi's Byakugan being potent enough to awaken Tenseigan.