When shifting on quicksoil glass panes, you can perpetually build up speed on the edge of a pane. This is because when on the edge of a pane, you are still over the same blockpos. This doesn't happen on quicksoil blocks because you change blockpos

Needs confirmation in 0.2.0

(Or at least, I imagine that's what's causing it)

Oh, by edge of a pane I mean like an end. You'll be stationary, see the screen do the fast speed fov effect, and when you unshift you'll go flying off.

Is fixing this going to require talking about parallel universes?

Ah, it's not a bug - it's just a sequence break for speedrunners