Use Cases Lost with the Removal of Functions Proxies in Function V4

It was suddenly announced that Functions Proxies will be removed from Azure Functions v4.

>Azure Functions Proxies are no longer supported in 4.x. You are recommended to use Azure API Management.

https://docs.microsoft.com/en-us/azure/azure-functions/functions-versions?tabs=csharp%2Cv4#breaking-changes-between-3x-and-4x

It is unacceptable for users to remove frequently used functions without any notice of discontinuation. Deletion without communication with the user will lead to distrust of the product.

The breaking changes in Functions V4 were identified in the Proposal in the repository below, but the Proxies were removed without a Proposal being created.

https://github.com/Azure/azure-functions/issues?q=is%3Aissue+label%3A%22Breaking+Change%3A+Approved%22+is%3A%22closed+OR+open%22

We believe that we are recommending a move to the Consumption Tier of API Management, but the current APIM Consumption Tier lacks some features and does not fully cover the use cases of Functions Proxies.

### Domain root level access

Requests to override the Azure Functions route level and return static pages have all been accomplished using Functions Proxies.

- https://github.com/Azure/azure-functions-host/issues/848#issuecomment-281696890

The members of the development team had consolidated their requests for root level access into this issue. In other words, it is a feature that cannot be achieved without using proxies.

### Easy Auth

While API Management is only for APIs, Functions Proxies have also been used to deliver web applications. Its flexibility has been a big advantage.

### VNET Integration

The Consumption Tier of API Management cannot configure VNET Integration, and therefore cannot achieve a secure network design. This is a requirement for enterprise applications, but is easily achieved in Azure Functions Proxies.

### Managed certificate

Currently, Managed certificate is only provided for CDN / Front Door / App Service, and API Management does not provide a quick HTTPS protected API like App Service.