Adding multiple scopes to a Compute Engine VM instance on Google Cloud not working

I'm trying to create a Compute Engine VM instance sample in Google Cloud that has an associated startup script startup_script.sh. On startup, I would like to have access to files that I have stored in a Cloud Source Repository. As such, in this script, I clone a repository using

gcloud source repos clone <repo name> --project=<project name>

Additionally, startup_script.sh also runs commands such as

gcloud iam service-accounts keys create key.json --iam-account <account>

which creates .json credentials, and

EXTERNAL_IP = $(gcloud compute instances describe sample --format='get(networkInterfaces[0].accessConfigs[0].natIP)' --zone=us-central1-a)

to get the external IP of the VM within the VM. To run these commands without any errors, I found that I need partial or full access to multiple Cloud API access scopes.

If I manually edit the scopes of the VM after I've already created it to allow for this and restart it, startup_script.sh runs fine, i.e. I can see the results of each command completing successfully. However, I would like to assign these scopes upon creation of the VM and not have to manually edit scopes after the fact. I found in the documentation that in order to do this, I can run

gcloud compute instances create sample --image-family=ubuntu-1804-lts --image-project=ubuntu-os-cloud --metadata-from-file=startup-script=startup_script.sh --zone=us-central1-a --scopes=[cloud-platform, cloud-source-repos, default]

When I run this command in the Cloud Shell, however, I can either only add one scope at a time, i.e. --scopes=cloud_platform, or if I try to enter multiple scopes as shown in the command above, I get

ERROR: (gcloud.compute.instances.create) unrecognized arguments:
  cloud-source-repos,
  default]

Adding multiple scopes as the documentation suggests doesn't seem to work. I get a similar error when use the scope's URI instead of it's alias.

Any obvious reasons as to why this may be happening? I feel this may have to do with the service account (or lack thereof) associated with the sample VM, but I'm not entirely familiar with this.

BONUS: Ideally I would like to run the VM creation cloud shell command in a cloudbuild.yaml file, which I have as

steps:
   - name: 'gcr.io/cloud-builders/gcloud'
   entrypoint: gcloud
   args: ['compute', 'instances', 'create', 'sample', '--image-family=ubuntu-1804-lts', '--image-project=ubuntu-os-cloud', '--metadata-from-file=startup-script=startup_sample.sh', '--zone=us-central1-a', '--scopes=[cloud-platform, cloud-source-repos, default]']

I can submit the build using

gcloud builds submit --config cloudbuild.yaml .

Are there any issues with the way I've setup this cloudbuild.yaml?

Adding multiple scopes as the documentation suggests doesn't seem to work

Please use the this command with --scopes=cloud-platform,cloud-source-reposCreated and not --scopes=[cloud-platform, cloud-source-repos, default]:

gcloud compute instances create sample --image-family=ubuntu-1804-lts --image-project=ubuntu-os-cloud  --zone=us-central1-a --scopes=cloud-platform,cloud-source-reposCreated 

[https://www.googleapis.com/compute/v1/projects/wave25-vladoi/zones/us-central1-a/instances/sample].
NAME    ZONE           MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP    STATUS
sample  us-central1-a  n1-standard-1               10.128.0.17  35.238.166.75  RUNNING

Also consider @John Hanley comment.