Lately an online tool of a client I am using for years doesn't show scroll bars anymore

Has anyone reported this before? I am working as a contractor for a BigTech company. I am using an online platform/tool of theirs for several years now but after a recent update the work area doesn't show scroll bars anymore. That means I cannot scroll the editor window and can't go beyond the first page. This makes working (and earning money) almost impossible. As even for the tiniest edit I have to download huge tasks which is extremely time-consuming. An inquiry with my manager there indicated that other contractors on firefox experience the same issue. so they consider it a firefox compatibility issue of some kind. They gave me the advice to use Chrome, Edge or Safri instead. Well, I use firefox because I do not want to use Chrome/Edge... Don't know about Safari but my PC is on Windows... Any idea what can cause it and how to resolve the issue?