How to set Win32_ProcessStartup parameters in Powershell?

This is the PS-snippet that I have so far. Starting the detached process works fine, but I cannot set the ProcessStartupInformation. How can this be done? Also this code sometimes comes up with error code 8 or 21 in a fresh PS instance. I could not find a pattern for this error till now. But it happens, when I run this code multiple times in a row without closing the previously created notepad-process.

$startup = Get-WmiObject Win32_ProcessStartup 
$arguments = @{
    CommandLine = 'notepad.exe' # or just 'notepad'?
    CurrentDirectory = 'c:\windows\system32'
    # ProcessStartupInformation = $startup
}
Invoke-CimMethod -ClassName Win32_Process -MethodName Create -Arguments $arguments

For any reason, the command "Get-CimInstance -ClassName Win32_ProcessStartup" is not returning anything in latest Windows 11 here.

MSDN has this VB-sample code, but I dont know how to convert this into Powershell:

Const HIDDEN_WINDOW = 12
strComputer = "."
Set objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set objStartup = objWMIService.Get("Win32_ProcessStartup")
Set objConfig = objStartup.SpawnInstance_
objConfig.ShowWindow = HIDDEN_WINDOW
Set objProcess = GetObject("winmgmts:root\cimv2:Win32_Process")
errReturn = objProcess.Create("Notepad.exe", null, objConfig, intProcessID)

Or should I better use any other (more reliable) option to start a detached process?

Update: This is the code I am now using, but still getting this annoying error codes 8 and 21 when running it multiple times:

# sample code starting a detached notepad-process 

# referennce: 
# https://learn.microsoft.com/en-us/windows/win32/cimwin32prov/win32-processstartup#properties
# https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-showwindow

$startup = [ciminstance]::new((Get-CimClass 'Win32_ProcessStartup'))
$startup.ShowWindow = 5        # hidden=0, normal=5, minimize=7, hidden=12
$startup.PriorityClass = 16384 # below normal

$arguments = @{
    CommandLine = 'notepad.exe'
    CurrentDirectory = 'c:\windows\system32'
    ProcessStartupInformation = $startup
}
Invoke-CimMethod -ClassName Win32_Process -MethodName Create -Arguments $arguments

Create a [ciminstance] object and pass the class as the first argument:

# create and configure startup object
$processStartup = [ciminstance]::new((Get-CimClass 'Win32_ProcessStartup'))
$processStartup.ShowWindow = 12

# attach to argument table
$arguments['ProcessStartupInformation'] = $processStartup