@Cassie I see the "lerp" effect is not there on mobile. When I test on my iPhone with ScrollSmoother init, and without. It feels different. For example if you scroll to the top, or the bottom is won't stop/end the same as without ScrollSmoother, it stills smooths out this motion.
I also tested the codepen you posted, and I don't have that problem there. So maybe it has something to do with my CSS.
Will edit if I know the problem.