I have been testing in sandbox and i do not know the full extent of what is happening, but at a baseline, geists headshot dmg multiplier is not 2x, it's around 1.9x. (this might be intended idk if it is intended i would love to have this noted somewhere) Her damage amp appears to not affect her...
I would wager it's related to changes with keybinds and the ability to rebind channel cancels, as geist was one of the special cases before the patch with a different channel cancel key, and since the patch I can no longer jump during life drain, which is a pretty significant disadvantage