@Mark Buckley Welcome to Microsoft Q&A thanks for posting your question.
If your compute resources are underutilized, consider scaling down your compute tier or size (vCores). If your workload doesn't require continuous full compute capacity, switching to the Burstable compute tier might be more cost-effective.
Use Azure Advisor to get recommendations on server right-sizing and other cost optimization strategies. It provides daily checks and suggestions based on your server's performance history
https://learn.microsoft.com/en-us/azure/mysql/flexible-server/concepts-service-tiers-storage
https://learn.microsoft.com/en-us/azure/mysql/flexible-server/concepts-azure-advisor-recommendations
Regards
Geetha