When you run a database within your Kubernetes cluster, high availability (HA), backup, and DR are your responsibilities. Setting up cron jobs to take backups and store them separately, and also ensuring that the instance is up and running, makes this a complicated operation. As a developer or an operator, running MySQL in production will not be your core competency and it is also unlikely to be for your company. Just as we don't manage our own Kubernetes cluster (we use the managed Kubernetes service), for production, we recommend that you keep life simple by using the managed option.
You can refer to https://docs.microsoft.com/en-us/azure/mysql/concepts-backup to find up-to-date information on the backup frequency, replication, and restore options.