Try this:

Type about:config in the address bar > press Enter

- click 'Accept the risk and continue'

- search for webgl.disabled > if the value is false, change it to true

So, it was false, and changing it to true did nothing.

However, somehow, changing it back to false afterwards seems to have fixed things.

I'm not sure why that worked, but I guess 'turn it off and on again' works in the weirdest places.

Thanks!

Update: It has now stopped working again, and doing the same solution isn't working this time. :/

Enter about:support in the address bar > search (ctrl-f) for WebGL 1 Driver Renderer. What is listed?

Is webgl.enable-webgl2 set to true?

What happens at https://get.webgl.org/webgl2/?

WebGL 1 Driver Renderer: Google Inc. (AMD) -- ANGLE (AMD, AMD Radeon RX 6600 XT Direct3D11 vs_5_0 ps_5_0, D3D11-32.0.13031.3015)

(WebGL 2 Driver Renderer is identical if that matters)

webgl.enable-webgl2 is set to true, yes

the website gives me the same message as for the normal WebGL site but with WebGL2 instead. Namely: "Hmm. While your browser seems to support WebGL2, it is disabled or unavailable. If possible, please ensure that you are running the latest drivers for your video card."

My drivers end with 4255, not 3015. Not sure it makes any difference though. The only way you can update Direct3D is via Win updates, so make sure you have the latest. You could also submit a support ticket at AMD (https://www.amd.com/en/forms/contact-us/support.html).

After looking things over on the AMD side, I ended up uninstalling and reinstalling the drivers. I ended up with the same version number, but it seems to be working so far. I'll give it a few days to be sure before marking this as solved, given the previous false positive I got, though.

Update: As before, it has stopped working again.

Try Troubleshoot mode (https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode) and see what happens.

Troubleshoot mode has also resolved it, probably temporarily

However, I think I know why it's happening now - my graphics card has been occasionally crashing for no apparent reason. It's been doing it periodically for years, so I didn't connect it to this, but it's possible that it's causing the "until I restart Firefox" WebGL issues I've been having.

It's an intermittent issue, so will be annoying to test that, but will respond here again once I have an answer on that one way or the other.

Go back to normal mode and try turning off hardware acceleration:

Go to FF Menu > Settings and enter 'hardware' (no quotes) in the search box

- uncheck 'Use recommended performance settings'

- uncheck 'Use hardware acceleration when available'

- close the tab and restart FF

I appreciate the additional support, but I was able to confirm just now; the issue is not actually with firefox, it's the weird issue with my graphics card causing it as a byproduct and I can fix it by just restarting firefox whenever my graphics card crashes.

Thanks for all the troubleshooting help to let me figure out that that was what the issue was, though.