Discrete GPU is not used even when using "Launch using dedicated graphics card" option

[Pierre Equoy]

Image: 22.04 beta
Device: Dell Precision 7760 (with NVIDIA Corporation GA104GLM [RTX A5000 Mobile] GPU)
Desktop: GNOME running Wayland
Firefox snap: 98.0.2-1 (1154)

Summary
=======

Firefox, a snap application, does not see the Discrete GPU, even when run using the appropriate option ("Launch using Discrete Graphics Card"). The problem does not seem to happen with non-snap applications.

Steps to reproduce
==================

1. Install 22.04 beta image using third party software (nvidia proprietary drivers)
2. Launch Firefox by left-clicking on the icon
3. Go to about:support, and check the GPU information
4. Close Firefox
5. Right click on Firefox icon, and select "Launch using Discrete Graphics Card"
6. Repeat step 3

Expected result
===============

In step 3, the Active GPU should be the Integrated GPU (in my case, Intel).
In step 6, the Active GPU should be the Discrete GPU (in my case, Nvidia).

Actual result
=============

In both step 3 and step 6, the active GPU is the integrated one:

Graphics
--------

GPU #1
Active: Yes
Description: Mesa Intel(R) UHD Graphics (TGL GT1)
Vendor ID: 0x8086
Device ID: 0x9a70
Driver Vendor: mesa/iris
Driver Version: 21.0.3.0
RAM: 0
GPU #2
Active: No
Vendor ID: 0x10de
Device ID: 0x24b6

It might be a snap problem, because if I run the same test with a non-snap application (e.g. Terminal), it works as expected:

1. Open the terminal application, and run (you may have to install mesa-utils package):

$ glxinfo | grep "OpenGL vendor"
OpenGL vendor string: Intel

2. Close the terminal, right click on its icon, select "Launch using Discrete Graphics Card" and repeat step 1:

$ glxinfo | grep "OpenGL vendor"
OpenGL vendor string: NVIDIA Corporation

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: firefox 1:1snap1-0ubuntu2
ProcVersionSignature: Ubuntu 5.15.0-23.23-generic 5.15.27
Uname: Linux 5.15.0-23-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu80
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Apr 1 15:46:39 2022
InstallationDate: Installed on 2022-04-01 (0 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Beta amd64 (20220329.1)
Snap.Changes: no changes found
SourcePackage: firefox
UpgradeStatus: No upgrade log present (probably fresh install)

[Pierre Equoy (pieq)]

More logs coming from sosreport.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.