Thanks for asking question! If I am right, you are following this Exercise on Creating a web app in the Azure portal, As its mentioned here:
“This module requires a sandbox to complete. A sandbox gives you access to Azure resources. Your Azure subscription will not be charged. The sandbox may only be used to complete training on Microsoft Learn. Use for any other reason is prohibited and may result in permanent loss of access to the sandbox.
Due to the impact of the global health pandemic, Azure resources are being prioritized towards health and safety organizations. You may experience some issues when you deploy resources used in the exercises. Please try again or choose a different region. For more information, see Azure blog post - Update #3: Business continuity with Azure.”
For more information see Azure blog post - March 28: Update #2 on Microsoft cloud services continuity.
More details : https://learn.microsoft.com/en-us/learn/support/troubleshooting