Board Thread:Theories and Speculation/@comment-39544279-20200621094206/@comment-6769189-20200621102452

Casting genjutsu involved forcing ones own chakra into the target to take control of their chakra to manipulate their senses.

Its possible that the act of casting genjutsu on someone who doesnt ha e chakra gives that person chakra, similar to how Hagoromo gave people the ability to mold chakra, except forced by a genjutsu user