I'd love if you can show me how to reproduce this bug.
I just don't have this experience with SPAs breaking. I actually have no idea where it's coming from.
I can see what is happening there: the popup removes scrolling (because of the overlay) but the back button doesn't restore it.
This certainly does lend to the conclusion that managing page state in a SPA is not trivial.
It seems to be a fast and responsive site when it works, though.
LOL.
Y'all, I love speed as much as anyone, but your development priorities should be 1) it works and 2) it's fast.
Using HTML links where 1) is never in doubt and all focus can be placed on 2) seems like good engineering to me.
Reinventing browser navigation is like building a rocket. You should be really, really sure that you need to do it before you try.
A great example of how it's quite difficult to reimplement stuff that works perfectly well on traditional pages.
(At least they seem to haven gotten rid of some of the dark patterns they had in the past, that's nice to see)
EDIT: and within a minute more found another state bug :D
Yes, you can make perfect SPAs, but many people fail and it's a good question if the effort required to do it properly is worth it.