This is basically a site bug.
They explicitly ask for this scrollbar -- they style the element in question with:
And then in Chrome and Edge, they hide the scrollbar by setting a negative "margin-right". It looks like this:
<div class="panelWrapper multi left noScroll" style="margin-right: -17px;">
This ends up clipping the scrollbar, because this element's parent has
overflow:hidden, so it hides the negative-margin-area on its child (which is the child's scrollbar area).
But in Firefox, they give this element "margin-right: 0px". On Linux, that's fine because scroll tracks are transparent (and maybe they're trying to use 0px for that "we figured out that scroll tracks are transparent" scenario?) But on Windows, scroll tracks are not transparent, so they need to give us a similar margin-right bump that they're giving to Chrome in order to hide the scrollbar.