Clarification on Outbound IP Addresses for Platform-Level Features

I have questions about the section regarding [outbound IP addresses](https://learn.microsoft.com/en-us/azure/azure-functions/ip-addresses?tabs=azurecli#find-outbound-ip-addresses) for platform-level features like Key Vault references.

The documentation states:

> For some platform-level features such as Key Vault references, the origin IP might not be one of the outbound IPs, and you should not configure the target resource to rely on these specific addresses. It is recommended that the app instead use a virtual network integration, as the platform will route traffic to the target resource through that network.

Questions for Clarification:

- Frequency of Different Origin IP: How often would the origin IP address differ from the list of outbound IP addresses provided for Azure Functions? Are there any specific scenarios or configurations where this is more likely to occur?
- Handling Blocked Origin IP: If the origin IP isn't in the provided list and gets blocked, what implications does this have for the function's operation?
- Lifecycle Awareness: At what point in the lifecycle of the Azure Function (e.g., app start, on each request) would we be able to determine if the origin IP address is different from the outbound IP addresses?
- Error Reporting: In cases where there is an IP mismatch leading to connectivity issues, how is the error reported or bubbled up? Is there a specific exception or log that we should monitor for troubleshooting?