Not sure why bu looks like that running a VM (Windows 10 in this case) on BigSur (11.2.1) is making launchd quite busy (excessively writing to disk). Once the VM is closed everything came back to normal. Over the last 3 days I have 120GB+ of disk writing.
I think that Activity Monitor is showing you the wrong process..
The reason for the is that launchd itself is the "LaunchDaemon" and it is used to manage processes, not to write things to disk. It would be very strange if it did write GB's of data to disk...
Snippet from the man page:
launchd -- System wide and per-user daemon/agent manager
launchd manages processes, both for the system as a whole and for individual users.
If you then go look around BS to see what services related to VMware Fusion could be related then you'll bump into these vmware related services:
% ls /Library/LaunchDaemons
com.vmware.IDHelper.plist com.vmware.MountHelper.plist com.vmware.DiskHelper.plist
The DiskHelper.plist looks like it will be the most likely "suspect".
The plist file takes care of starting the service:
If you look into that one with strings then you might notice that it is able to communicate via XPC.
So launchd takes care of the service running and VMware Fusion is talking to it via the XPC interprocess communication protocol.
IOW.. nothing weird is going on.