I want to set the old context menu for all new user in Windows 11. The solution for the current user is to set the following reg-key:
HKCU:SoftwareClassesCLSID{86ca1aa0-34aa-4e8b-a509-50c905bae2a2}InprocServer32
Then the explorer has to restart.

With this reg-file I place a powershell command in the RunOnce section:

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunOnce]
"OldContextMenu"="powershell -Command "$regpath="HKCU:\SOFTWARE\Classes\CLSID\{86ca1aa0-34aa-4e8b-a509-50c905bae2a2}\InprocServer32" ; if(-not (Test-Path $regpath)){New-Item -Path $regpath -Force} ; Set-Item -Path $regpath -Value "" ; $null=Read-Host ; Stop-Process -Processname Explorer -WarningAction SilentlyContinue -ErrorAction SilentlyContinue -force""

The resulting PowerShell commands run well in a PowerShell window with or without admin rights:

$regpath="HKCU:SOFTWAREClassesCLSID{86ca1aa0-34aa-4e8b-a509-50c905bae2a2}InprocServer32" ; if(-not (Test-Path $regpath)){New-Item -Path $regpath -Force} ; Set-Item -Path $regpath -Value "" ; $null=Read-Host ; Stop-Process -Processname Explorer -WarningAction SilentlyContinue -ErrorAction SilentlyContinue -force

Howto get this work in the RunOnce section?

I see the PowerShell window open at the beginning of the logon, but the code is not successful.
Tried to place an input line in the code for debugging purposes.