Hi @MITRADebarthaGECoreTechCyber-2843,
The --html flag actually defaults to Windows OS. As a workaround, you can add a package.json file the root directory and remove the --html arg. This will tell the CLI to upload as a nodejs runtime. See https://github.com/Azure/app-service-linux-docs/blob/master/AzWebAppUP/runtime_detection.md for more details or to elect a different runtime other than node.
I also created a new issue requesting that the --html arg doesn't default to Windows OS where you can add any additional details you like.