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.
Can definitely attest to this. Librewolf is my daily and I run it pretty aggressively (uBO options/lists, strict blocking DNS, etc) and sometimes I'm left scratching my head where things break. Recently had an aha-moment that felt triumphant when disabling the limit cross-origin referers, as silly as it sounds. Alas, I guess I prefer it this way.
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.