After a Windows server was migrated to the cloud platform, the used space of C: drive increased at least 1 GB.
This is normal because the size of the paging file, used for virtual memory, tends to be larger after the migration is complete.
The Folder Options dialog box is displayed.

The pagefile.sys file on the target server is larger than that on the source server.
The size difference of pagefile.sys on the two servers should account for the difference in used space.
The System Properties dialog box is displayed.
The Performance Options page is displayed.
The Virtual Memory is displayed.
You can see that the target server uses Automatically manage paging file size for all drives. That is, the size of virtual memory file pagefile.sys on the target server is equal to the size of file Installed Memory (RAM) on the server.
If the size of file Installed Memory (RAM) on the target server is different from that on the source server, the used space of C: drive on the target server is inconsistent with that on the source server.