Board Thread:Theories and Speculation/@comment-46486865-20200801172327/@comment-32685487-20200802000110

Toneri was implied to have done something to Boruto himself and not just his eye. We don't know when that happened but it would have had to have been before Boruto awakened the Jogan. Urashiki and the other main clan members also seemed to not be so happy that Toneri did that, whatever that is. Also TOneri was just beaten to the point he couldn't keep his Tenseigan active, he then loses the eyeballs that he stole. In short Toneri awakened the Tenseigan himself so if he was to get ahold of some Hyuga Byakugan again they would start the process of evolving into Tenseigan again.