You recover Microsoft 365 data from a backup (via Online Dashboard).
Entire mailbox is selected for recovery.
After recovery, the operation status is "succeeded with warnings":
Cannot recover Microsoft 365 mailbox item ID: ..... in folder .... is skipped because size is larger than 4MB limit.
Data is recovered successfully except the attachment mentioned in the warning.
Microsoft 365 limitation: letters that contain attachments that are larger than 4MB cannot be restored.