A Microsoft file hosting and synchronization service.
Hi Milan,
Welcome to Microsoft Community and I'm glad to offer the support.
Based on the shared screenshot, it should be the automatic notification when users delete a file from OneDrive desktop application. See the following screenshots from my tests just now by deleting a file from OneDrive folder in File Explorer.
Hence, if you are in the situation as above, then the message should be popped up because of some deletion action of a file named 'E04******.pkgdat'. For the detailed information of this deleted file, you can check from Recycle Bin in OneDrive Online. See: Restore deleted files or folders in OneDrive (microsoft.com)
Meanwhile, if you want to avoid receiving such an warning box each time you delete a file from OneDrive desktop app, check on the box Don't show the reminder again.
If you have any further concern about this situation like you have never added such a pkgdat file into your OneDrive but facing the message, feel free to back with us and provide some more screenshots of the search results via the file name in OneDrive Online and Recycle Bin.
Best Regards,
Mia