[BUG] 'salt-call grains.item gpus:vendor' lists only a single GPU vendor

Description

All GPU vendors and GPU model names are visible when running:

# salt-call grains.item gpus
local:
    ----------
    gpus:
        |_
          ----------
          model:
              G200eR2
          vendor:
              matrox
        |_
          ----------
          model:
              GK110GL [Tesla K20m]
          vendor:
              nvidia

However, only a single one is shown when running:

# salt-call grains.item gpus:vendor
local:
    ----------
    gpus:vendor:
        matrox

On different machines, also with Matrox and Nvidia GPUs, the result will differ and the latter vendor is shown:

# salt-call grains.item gpus:vendor
local:
    ----------
    gpus:vendor:
        nvidia

The results are deterministic insofar as not to flip between vendors on the same machine but I can't seem to find the pattern why on some machines it is one and on other machines the other vendor is shown.

This makes it impossible to target machines using that particular grain, e.g.:

  'gpus:vendor:nvidia':
    - match: grain
    - foo

will only run/apply foo to machines which return nvidia as the first, and only, vendor.

Setup
This can be observed without any specific Salt configuration in place.

Please be as specific as possible and give set-up details.

• on-prem machine
• VM (Virtualbox, KVM, etc. please specify)
• VM running on a cloud service, please be explicit and add details
• container (Kubernetes, Docker, containerd, etc. please specify)
• or a combination, please be explicit
• jails if it is FreeBSD
• classic packaging
• onedir packaging
• used bootstrap to install

Steps to Reproduce the behavior

Run salt-call grains.item gpus:vendor on any machine with GPUs from several vendors.

Expected behavior

Have all vendors returned like so:

# salt-call grains.item gpus:vendor
local:
    ----------
    gpus:vendor:
        - intel
        - matrox
        - nvidia

The same could be extended to gpus:model name:

# salt-call grains.item gpus:model
local:
    ----------
    gpus:model:
        - Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller
        - RV710/M92 [Mobility Radeon HD 4330/4350/4550]
        - GK180GL [Tesla K40c]

Versions Report

# salt --versions-report
Salt Version:
          Salt: 3005.1
 
Dependency Versions:
          cffi: Not Installed
      cherrypy: Not Installed
      dateutil: 2.6.1
     docker-py: Not Installed
         gitdb: 2.0.3
     gitpython: 2.1.8
        Jinja2: 2.10
       libgit2: 0.26.0
      M2Crypto: Not Installed
          Mako: 1.0.7
       msgpack: 0.5.6
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     pycparser: Not Installed
      pycrypto: 2.6.1
  pycryptodome: 3.4.7
        pygit2: 0.26.2
        Python: 3.6.9 (default, Jun 29 2022, 11:45:57)
  python-gnupg: 0.4.1
        PyYAML: 3.12
         PyZMQ: 17.1.2
         smmap: 2.0.3
       timelib: Not Installed
       Tornado: 4.5.3
           ZMQ: 4.2.5
 
System Versions:
          dist: ubuntu 18.04 Bionic Beaver
        locale: UTF-8
       machine: x86_64
       release: 5.4.0-132-generic
        system: Linux
       version: Ubuntu 18.04 Bionic Beaver

Start by reproducing the behavior with salt-call grains.item gpus and salt-call grains.item gpus:vendor on a machine with GPUs from multiple vendors. Trace the gpus grain handling and compare the nested output with the gpus:vendor and gpus:model lookups. Done means all detected vendors and models are returned as lists, as shown in the expected output.