Ref.: https://docs.microsoft.com/en-us/azure/storage/files/storage-how-to-create-file-share?tabs=azure-portal#basics

To create a FileStorage storage account, ensure the Performance radio button is set to Premium and Fileshares is selected in the Premium account type drop-down list.

When I change to the following:

az.storage.StorageAccount(
    kind=az_storage.Kind.FILE_STORAGE,  # TO MATCH PREMIUM_LRS
    sku=az_storage.SkuArgs(
        name=az_storage.SkuName.PREMIUM_LRS,
    ),
...
)

... I start getting this instead:

azure-native:storage:FileShare (fileShare):
    error: autorest/azure: Service returned an error. Status=400 Code="InvalidHeaderValue" Message="The value for one of the HTTP headers is not in the correct format.\nRequestId:3d8b324b-d01a-0068-25ea-453b7f000000\nTime:2021-05-10T22:18:10.0964124Z"

Or perhaps this is more relevant: https://github.com/pulumi/pulumi-azure-native/issues/786 - generally suspecting if the api specs for fileshare storage accounts published by Azure have an issue. Could you try and do this through the AZ cli?