@Ben Liu This might be two separate issues.
Are you getting the same message"
The existing Azure Support offer has been discontinued on June 30, 2024. Beginning July 1, 2024, all customers who do not already have a paid support plan (Microsoft Unified, ProDirect support, etc.) will need to purchase a support plan if they wish to maintain technical support coverage. Customers will retain access to the subscription management and billing support services available to all Azure customers at no charge.
- Customers wishing to transact support on their Enterprise Agreement should contact their Microsoft representative or partner.
- Customers wishing to transact support on their Microsoft Customer Agreement, can purchase support online in the Azure Portal.
The webpage has been updated on July 1, 2024 to note that the promotional offer has come to an end."
https://azure.microsoft.com/en-us/updates/v2/Azure-Support-Plan-Discontinued
Regarding the Zone Redundancy issue, it might be specific to your SQL Managed Instance.
West us 3 is supported region but some types of subscriptions are not supported when deploying Managed Instances dbs.
You can check through support ticket why it was disabled for your account.
Regards,
Oury