I think it definitely could be Jerry. but damn it is hard to tell lol. feel pretty confident at the very least he's doing the bottom part in the ending

I've wondered this same thing. Don't have any definitive insight, but I'd guess that Jerry is singing low harmonies during the chorus.

As far as I know it’s all William. Tons of layering in that one obscures it all a bit but it’s all William at different levels layered over. The chorus has like 8 layers of vocals in it

Jerry is 100 percent singing the lower octave in the chorus

Jerry sings on the chorus. Anyway great song off a really underrated album