Thank you for getting back and apologies for the delay here.
My question is around what are the uses cases of using both service/private endpoints together. Is it an improvement of security over something that is not in a hub/spoke design (legacy) . thanks
Azure Service Endpoints and Private Endpoints are quite similar services where they help with network restrictions. The typical use cases are usually between using Service Endpoints or Private endpoints
The benefit of Service endpoints is that they are more straight forward to set-up and less complex than Azure Private endpoint. Although Service endpoints are less secure the reason being the PaaS resources are still accessible on their public IPs and the traffic does exit your virtual network.
Although private endpoint is more complex to set-up they are more secure as the traffic does not exit the virtual network and the PaaS resources are accessed using private IP.
This a very good blog post you can refer to for the comparison between the two.
As documented here Private endpoints can be created in subnets that use Service Endpoints. Although I will recommend the use of private endpoints only instead of using both for security reason mentioned above and more and more Azure Services are offering private endpoint support as compared to Service endpoints. Depending on your set-up, down the line suppose customers who are accessing a resource using Service endpoint might need to access another PaaS resource which supports only private endpoint this might increase the engineering complexity.
Hope this helps! Please let me know if you have any additional questions. Thank you!
Please "Accept the answer" if the information helped you. This will help us and others in the community as well.