Routing preference is a feature that allows you to configure how network traffic is routed to your storage account from clients over the internet. By default, traffic from the internet is routed to the public endpoint of your storage account over the Microsoft global network, which is optimized for low-latency path selection and high reliability. Both inbound and outbound traffic are routed through the point of presence (POP) that is closest to the client. This ensures that traffic to and from your storage account traverses over the Microsoft global network for the bulk of its path, maximizing network performance. You can also change the routing preference to use internet routing, which minimizes the traversal of your traffic over the Microsoft global network, handing it off to the transit ISP at the earliest opportunity. This lowers networking costs, but may compromise network performance. Therefore, to ensure that inbound user traffic uses the Microsoft POP closest to the user's location, you should configure routing preference to use the Microsoft global network as the default routing option for your storage account.
Reference:
Network routing preference for Azure Storage
Configure network routing preference for Azure Storage