Board Thread:Theories and Speculation/@comment-26479810-20191214162345/@comment-9782468-20191223014712

@Flatzone exactly, he took the Ten Tails chakra from its body and made 9 self-sustaining entities of chakra. So doing so with his own chakra doesn't seem far-fetched.

You can make any explanation for any number of unexplained things in the series, but without actual proof your explanation is just a theory. And considering how Kishi is generally on the nose about everything in the series, it seems more likely he'd make note of them losing his chakra if that were the case.