Not sure what caused this issue (I'd guess the backup application did), but your current virtual disks have snapshots with the names in an unusual order, where the delta files have the names which are usually assigned to the flat file!? In addition to this the virtual disk size
NEXDBTV01.vmdk -> NEXDBTV01-delta.vmdk
NEXDBTV01-ac1eb6efaa73e4a.vmdk -> NEXDBTV01-ac1eb6efaa73e4a-flat.vmdk
NEXDBTV01_1.vmdk -> NEXDBTV01_1-delta.vmdk
NEXDBTV01_1-9ace2ad6c00b0c6.vmdk -> NEXDBTV01_1-9ace2ad6c00b0c6-flat.vmdk
NEXDBTV01_2.vmdk -> NEXDBTV01_2-delta.vmdk
NEXDBTV01_2-c90359261cca5b0.vmdk -> NEXDBTV01_2-c90359261cca5b0-flat.vmdk
What I would do is to run "Delete All" from the "Snapshot Manager" to merge the snapshot files into the base disks and then clean this up by either "Storage vMotion" the VM, which - depending on the version - should rename the files or clean this up manually (let me know if you need assistance with this).
André