Maintenance Note - https://gist.github.com/mark05e/0a04a54c1e8489c770bd91e4910d7df9

SetWall.ps1

#-------------------------------------------------------------------#
# ScriptName : SetWall.ps1                                          #
# Description : Force a Desktop wallpaper Refresh                   #
# Credits  : Unknown (if you know original creator, let us know)    #
#                                                                   #
# Date : 01 July 2020                                               #
# Ref  : https://c-nergy.be/blog/?p=15291                           #
#-------------------------------------------------------------------#

#Modify Path to the picture accordingly to reflect your infrastructure
$imgPath="C:\Temp\Wallpaper.jpg"

if (!(Test-Path $imgPath -PathType leaf))
{
    Write-Host "$imgPath not found!"
    Exit
}

$code = @' 
using System.Runtime.InteropServices; 
namespace Win32{ 
    
     public class Wallpaper{ 
        [DllImport("user32.dll", CharSet=CharSet.Auto)] 
         static extern int SystemParametersInfo (int uAction , int uParam , string lpvParam , int fuWinIni) ; 
         
         public static void SetWallpaper(string thePath){ 
            SystemParametersInfo(20,0,thePath,3); 
         }
    }
 } 
'@

add-type $code 

#Apply the Change on the system 
[Win32.Wallpaper]::SetWallpaper($imgPath)