Welcome to the Community,
to me this looks like you created the VMs with thick provisioned virtual disks with a size of ~100GB on these datastores!?
What one usually does is to create multiple VM's on a single datastore (depending on the workload and size) and keep ~15-20% free disk space on a datastore.
To see what's the case, please post a screen shot of the datastore browser window(s) for the VM's showing all files with their sizes, time stamps, ...
André