Why are you asking this question in a Microsoft forum?
Firefox is a Mozilla product and if you have any problems with Firefox, you go to the Mozilla Firefox forums!
Your other source is Unity which is not a Microsoft product either!
Start at https://unity3d.com/
Microsoft does not provide support for Mozilla Firefox nor does it support Unity!!!
Search the internet for suggestions about your problem.
Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. ”