Powershell hashtable key clone weirdness

hashtable-key-clone-weirdness.ps1

# Use of script block for Group-Object -AsHashTable -Property breaks Keys.Clone()
# https://github.com/MicrosoftDocs/PowerShell-Docs/issues/8605

Write-Output "Using -Property Name"
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/group-object?view=powershell-7.2#example-1--group-files-by-extension
$files = Get-ChildItem -Path $PSHOME | Group-Object -Property Name -AsHashTable
Write-Output $files.Keys.count

# https://docs.microsoft.com/en-us/powershell/scripting/learn/deep-dives/everything-about-hashtable?view=powershell-7.2#iterating-hashtables
$files.Keys.Clone() | ForEach-Object { $files[$_] = 'test' }

Write-Output $files.Keys.count

Write-Output "Using -Property { `$_.Name } "
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/group-object?view=powershell-7.2#example-1--group-files-by-extension
$files = Get-ChildItem -Path $PSHOME | Group-Object -Property { $_.Name } -AsHashTable
Write-Output $files.Keys.count

# https://docs.microsoft.com/en-us/powershell/scripting/learn/deep-dives/everything-about-hashtable?view=powershell-7.2#iterating-hashtables
$files.Keys.Clone() | ForEach-Object { $files[$_] = 'test' }

Write-Output $files.Keys.count