The following key points will provide more insight into Azure SQL Managed Instances:

• If you are planning to use a precreated subnet for the SQL Managed Instance when you create it, ensure that the following conditions are met:
  • It is not a gateway subnet
  • There are not any service endpoints enabled for it
  • The subnet is not used by any other service
  • At least 16 IP addresses are available in the subnet
• Prepare subnet for managed instance is an option during the SQL Managed Instance creation, and it will handle the following:
  • It will create a user-defined table for the subnet 0.0.0.0/0 next-hop internet
  • A network security group will be created with some security rules, to be compliant with the Managed Instance deployment requirements
• When you increase the storage size in the Pricing tier blade, the custom amount to the nearest value divided by 32 would be rounded.
• You can make use of the hybrid use benefit and reuse an SQL Server license, saving up to 55% off the Managed Instance costs.