It is possible that there is a problem with the Rosetta 2 emulator. You can try to disable hardware acceleration in Firefox. *Options/Preferences -> General: Performance<br>remove checkmark: [ ] "Use recommended performance settings"<br>remove checkmark: [ ] "Use hardware acceleration when available" *https://support.mozilla.org/en-US/kb/performance-settings Close and restart Firefox after modifying the setting for changes to take effect. *https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems Note that Firefox 84 is scheduled for release later this week and that version might have better support for the Apple silicon M1 processor.