Hi,
Not all the features and resources are free, please check the FAQ and listed services in the free tier - https://azure.microsoft.com/en-gb/free/free-account-faq
Also you can contact the billing team for this issue - https://learn.microsoft.com/en-us/azure/azure-portal/supportability/how-to-create-azure-support-request#go-to-help--support-from-the-global-header
Hope this helps.
JS
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