For anyone having this problem on an Nvidia system, could you give the following a try? I don’t have such a system, so I’d be interested to see the results.
In a terminal, run snap run --shell firefox. This should drop you at a bash shell prompt within firefox’s confinement. In that shell, run the following commands:
export LD_LIBRARY_PATH=${LD_LIBRARY_PATH/"${SNAP_LIBRARY_PATH}:"/}
exec $SNAP/firefox.launcher
If Firefox starts up correctly, could you try opening about:support in a tab, and check to see whether it looks like the Nvidia drivers are being used in the Graphics section.
This will remove the LD_LIBRARY_PATH elements added by $SNAP/snap/command-chain/snapcraft-runner related to host system OpenGL drivers. The drivers should still be available later on in the library path, since $SNAP/snap/command-chain/desktop-launch also adds /var/lib/snapd/lib/gl to the end.
This will hopefully let the copy of the libEGL driver multiplexer (aka libglvnd) from the gnome-3-38-2004 shadow the copy from the host system, while still making the actual Nvidia driver library available on the search path.