hyper-v_snapshots

This is the solution that should be done first before any other solution. Just remove the lingerging backup checkpoint like you would a normal one via PowerShell (attention: check that you have a minimum of free space for the merge to be done without problems):

Get-VMSnapshot -VMName "VMWithLingeringBackupCheckpoint" | Remove-VMSnapshot

Just for the record: This command deletes all checkpoints

Get snapshot count for each VM

To count the number of snapshots/checkpoints for each VM in a Hyper-V host, you can use PowerShell. Here’s a refined version of your script that will do just that:

$vms = Get-VM
foreach ($vm in $vms) {
    $snapshotCount = (Get-VMSnapshot -VMName $vm.Name).Count
    Write-Output "$($vm.Name): $snapshotCount"
}

Explanation:

Get-VM retrieves all VMs on the host.
For each VM, Get-VMSnapshot fetches the snapshots, and .Count gives the number of snapshots.
Finally, it outputs the VM name along with its snapshot count.