The required packages I listed above are from Yoyogames documentation, as the game was made with Game Maker Studio 2. But it does seem odd that its showing a fault, though its compiled with YYC instead of the usual VM. Heres the link in terms of packages: https://help.yoyogames.com/hc/en-us/articles/360024186531
Also theres not much I can do with older firefox versions, but I would recommend checking out this UI tweak for Firefox, its what I use myself! https://github.com/black7375/Firefox-UI-Fix