Board Thread:Theories and Speculation/@comment-34997073-20200620190326/@comment-26636534-20200620211547

Yomotsu Hirasaka doesn't seem to be a rinnegan jutsu though, as Urashiki didn't have it active when performing it.

The Rinne-Sharingan seems to be more than just a rinnegan and sharingan combined. It could be Kaguya's own unique ability that then got watered down into the Sharingan with Indra's decedents.