If "sticky navbar" is turned off the subscriptions box disappears out of view if you scroll too far down. I noticed on version 0.3 if I changed -
position: on line 85 from "absolute" to "fixed"
top: on line 86 from "100%" to "9.5%" (9.5% didn't overlap with header and was aligned nicely across the top)
max-height: on line 89 from "100vh" to "90vh" - "95vh" (I use 93vh) then the sidebar stays fixed as you scroll.
then the sidebar stays fixed in place as you scroll, even with sticky-navbar turned off.
The only thing I don't like is that with the fixed sidebar it will overlap the footer at the bottom. I'm not sure how to make it not overlap, I literally just started googling this userscript stuff like 45 minutes ago. I'm guessing making the z-value of the footer a higher priority then the sidebar would make the sidebar scroll beneath the footer, but I don't know.