A few days ago I noticed that on my system firefox is not able to support webgl / hardware acceleration anymore as can be tested on webglreport.com.
Starting firefox via terminal gives me logs like these
[GFX1-]: glxtest: libEGL missing methods
[GFX1-]: glxtest: EGL test failed
[GFX1-]: More than 1 GPU vendor detected via PCI, cannot deduce vendor
[GFX1-]: PCI candidate 0x8086/0xa7a0
[GFX1-]: PCI candidate 0x10de/0x2860
Then I found this reddit thread that gave me the solution. It’s not firefox, it’s not a driver issue, but a problem introduced bynomachine, which is a package that I have installed. This bug is so random that I probably wouldn’t have found it. All credits to u/InnominateHomosapien on reddit! 
To then fix webgl support, do sudo /usr/NX/bin/nxserver --eglcapture no, reboot and that’s it.
Do note that remoting to your system via nomachine might not work anymore, which is fine for me as I only want to remote into other computers.
I thought it’s worth sharing this here for others to find and also to say thanks to u/InnominateHomosapien on reddit as I don’t have a reddit Account anymore since the 3rd party API fiasco.