@Vinix Wu - Edtung Thanks for posting your query on Microsoft Q&A.
From the screenshot, it looks like you do not have the diagnostics settings enabled to configure retention for logs and metrics sent to an Azure Storage account. Is that the right understanding on your end as well? Did you ever set up log retention for log data?
Follow the steps here and check if you have any diagnostics settings defined (Step 2): https://learn.microsoft.com/en-us/azure/azure-monitor/essentials/create-diagnostic-settings?tabs=portal
If not, you do not have to take any actions for the email received for the migration.