Board Thread:Theories and Speculation/@comment-1512913-20150116120105/@comment-3279282-20150121103946

I doubt Kishimoto would use an already existing term with a different meaning in a little site note, without any further explanation.

However, a possible explanation would simply be that Kaguya's Byakugan worked without chakra and after her bloodline diminished, the Byakugan did so as well and people needed chakra to activate them again.