It was alt-tabbing to discord loading updates (i close discord because it is banned in Russia and I idk if i got login credentials at me, so game closes as well)
I would think that's the VR support triggering it. Normally in steam we use -nohmd as a default launch option unless people select VR, but in the demo it's just running the .exe directly. I don't have my VR installed on this pc right now so i didn't notice that it was launching steamvr on the demo. You can launch the .exe with -nohmd and it will not start steamvr, i will figure out how to fix this for a next version.