I've run into this (it's in Librewolf, but is more obnoxious in Mull/IronFox on Android where I actually use this), where the privacy protections prevent the Jackbox games like Drawful from sending the contents of a drawing to Jackbox's servers. Both browsers don't fail - they just upload a rainbow pattern every time.

I use IronFox and LibreWolf as my daily drivers, but I keep Firefox installed alongside them for the inevitable site that just doesn't behave correctly. Not unlike having to reach for the big blue "E" in the bad old days.