az deploy complaining about `windowsConfiguration` trying to deploy a `Linux` VM ???

I'm suddenly getting a very weird error about `windowsConfiguration` trying to deploy a `Linux` VM. The VM is in my image gallery and I can deploy a VM using that image no problem using the portal, and this ARM template was working fine up until today, now it suddenly complains about windowsConfiguration? Is something busted in the ARM image builder cloud service?

```
> az deployment group create --resource-group clovett-rg \
--template-file trainervm_deployment_template.json \
--parameters trainervm_deployment_template.parameters.json

Please provide securestring value for 'adminPassword' (? for help):
```
```json
{
"status": "Failed",
"error": {
"code": "DeploymentFailed",
"message": "At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.",
"details": [
{
"code": "BadRequest",
"message": "{
"error": {
"code": "InvalidParameter",
"message": "The value of parameter windowsConfiguration is invalid.",
"target": "windowsConfiguration"
}
}
}
]
}
}
```

The arm templates is attached:

[trainervm_deployment_template.parameters.zip](https://github.com/Azure/azvmimagebuilder/files/12134609/trainervm_deployment_template.parameters.zip)

Note: I'm running this az command from a windows machine but that has never mattered before, nor should it.