On my Windows 10 desktop (for gaming), I use GNU/Linux virtual machines for normal computer work mainly in VMware Player which has better 3D graphics support and acceleration. Using VMs protects the host OS from exploits with Windows being a big target, and some malware will actually shut down when it sees its running in a virtual machine as this is how virus researchers attempt to study them. Consequently, this morning after installing some Mesa driver updates in my Ubuntu machines I was getting flickering with Firefox (Ubuntu KDE and Voyager Gnome). You have two workarounds if you experience this issue with any virtual machines, turn off 3D Acceleration for the virtual machine itself in VMware Player, or in Firefox disable hardware acceleration. I haven’t seen any issues with the OS itself, just Firefox, so this will get you working until the bug is corrected whether in VMware Player, the Mesa drivers, open-vm-tools, or possibly Firefox. My internet searches didn’t turn up much on this specific issue, just some past similar issues as there seems to be bugs with all the complex interactions. Side note on complexity and how they get this wrong, the latest Nvidia driver in Windows itself was buggy and I had computer crashes while trying to play Dirt Rally 2.0 which is an older game, and online comments showed lots of other people had issues with certain games, so Nvidia failed in testing and a lot of us had to revert to older drivers.
To disable hardware acceleration go into Firefox settings and scroll down to Performance and uncheck Use recommended performance settings, then the Use hardware acceleration when available will show and you can uncheck it. And after changing the settings I’d reload Firefox and then you’re free from the flickering bug. I didn’t notice any issues using Firefox and Youtube video playback still worked fine.
Consequently, my Voyager OS VM has a lot of visual effects added to Gnome, e.g. closing programs they burst into flames… and all this works fine with the one of exception of Firefox.