Your company is migrating their MySQL database to Cloud SQL and cannot afford any planned...

Open a support ticket in Google Cloud to prevent any maintenance in that MySQL instance during the month of December.

Use Cloud SQL maintenance settings to prevent any maintenance during the month of December.

Create MySQL read replicas in different zones so that, if any downtime occurs, the read replicas will act as the primary instance during the month of December.

Create a MySQL regional instance so that, if any downtime occurs, the standby instance will act as the primary instance during the month of December.