Hi Mohmmed Magdy,
Welcome to Microsoft Q&A forum.
As I understand, you are experiencing increase storage in Azure Database for MySQL Flexible Server.
Since your server is already stopped, please reduce the backup retention period if a longer retention of backup isn't required.
Scale down your compute tier or compute size (vCores) if compute is underutilized.
When logging is enabled for an Azure Database for MySQL flexible server instance, logs are available up to seven days from their creation. If the total size of the available logs exceeds 7 GB, then the oldest files are deleted until space is available. The 7-GB storage limit for server logs is available free of cost and can't be extended. Logs are rotated every 24 hours or 500 MB, whichever comes first.
This should help. If not, I would recommend you to please file a support ticket for deeper investigation and in case if you don't have a support plan, do let us know here so that we can check on other options to unblock you.
Thanks