Question GPU and CPU spiking only when plugged in? Hard/mysterious case

Apr 15, 2021

I have this notebook which has nvidia 940MX 2gb (also, i5 7th gen, 8gb ram, 250gb ssd 1tb HD, win 10)

When I open CS:GO with batteries on, the game runs smoothly, the gpu works fine. I get nice constant fps.
However, immediatly after I plug in the power supply, the gpu usage starts spikin from 100 to 0, very laggy. This happens to other games too.
The moment it starts spiking is when I plug in the power supply

I tried SEVERAL things. I cleaned the notebook's inside, I don't believe it's temperature thing otherwise it should occur plugged in or not
I tried to energy options configurations, every single possible way.
I tried adjusting configurations on nvidia contro panel, in many different ways.
I tried to find similar problem on youtube, google, every place on the internet. But nothing solved.
Yes, all my drivers are updated.
The problem seems to appear only when the notebook is running with the power supply.

The power supply itself seems ok to me, since it has no problem charging the notebook. So I don't know what could it be

Very weird problem. I beg someone to help me since I can't buy a new notebook now. I need to fix this one.
This forum is my last hope.